T A 

424 
Xs 



Issued June 12, 1911. 

U. S. DEPARTMENT OF AGRICULTURE, 

FOREST SERVICE— BULLETIN 84. 

HENRY S. GRAVES, Forester. 



PRESERVATIVE TREATMENT OF POLES. 



COMPILED BY 

WILLIAM H. KEMPFER, 

FOREST ASSISTANT. 





WASHINGTON: 

GOVERNMENT PRINTING OFFICE. 

1911. 



• r l^l 




Glass 'A 4^ 



Book 



/; 



Issued June 12, 10 11. 



U. S. DEPARTMENT OF AGRICULTURE, 

FOREST SERVICE— BULLETIN 84 



HENRY S. GRAVES, Forester. 



PRESERVATIVE TREATMENT OF POLES. 



COMPILED BY 

WILLIAM H. KEMPFER, 

FOREST ASSISTANT, 







WASHINGTON: 

GOVERNMENT PRINTING OFFICE, 

1911. 






^ 



LETTER OF TRANSMITTAL. 



U. S. Department of Agriculture, 

Forest Service, 
Washington, D. C, October 15, 1910. 
Sir: I have the honor to transmit herewith a manuscript entitled 
"Preservative Treatment of Poles," compiled by William H. Kempfer, 
Forest Assistant, and to recommend its publication as Bulletin 84 of 
the Forest Service. This bulletin is compiled in part from previous 
publications of the Forest Service, namely, Circulars 103, "Seasoning 
of Telephone and Telegraph Poles," by Henry Grinnell; No. 104, 
"Brush and Tank Pole Treatments," by Carl G. Crawford; No. 136, 
"Seasoning and Preservative Treatment of Arborvitse Poles," by 
C. Stowell Smith; and No. 147, "Progress in Chestnut Pole Preser- 
vation," by Howard F. Weiss. It presents, in addition, results of 
more recent experiments, especially those of O. T. Swan, Forest 
Assistant, who is also the author of the design for open-tank pole- 
treating plants. The inspection report contained in the Appendix 
was made by the compiler. 

Respectfully, Henry S. Graves, 

Forester. 
Hon. James Wilson, 

Secretary of Agriculture. 



U)N 



CONTENTS. 



Page. 

Introduction 7 

General principles of wood preservation 7 

Forest Service investigations 8 

Resume of projects : 9 

Results of seasoning tests. . . : 10 

Loss of weight 10 

Rate of seasoning 11 

Factors affecting seasoning 11 

Checking 12 

Shrinkage 13 

Brush method of treating poles 13 

Open-tank process of treating poles 14 

Manner of application 15 

Duration of treatment 15 

Temperature of hot bath 16 

Influence of rate of growth ; , . . 16 

Influence of moisture '. . 16 

Influence of season of cutting 17 

Influence of soaking in water 17 

Advantages and limitations of the open-tank process 17 

Results of treatments, by species _ 18 

Chestnut ." 18 

Brush treatments 18 

Tank treatments 19 

Southern white cedar 20 

Northern white cedar 20 

Brush treatments 21 

Tank treatments 21 

Western red cedar 22 

Brush treatments 22 

Tank treatment with creosote 23 

Tank treatment with zinc chlorid 25 

Other treatments 26 

Western yellow pine 26 

Brush treatments 26 

Tank treatments with creosote 27 

Tank treatments with zinc chlorid 28 

Tank treatment with creosote and zinc chlorid 28 

Tank treatments with crude petroleum 28 

Lodgepole pine 29 

Loblolly pine 29 

Cypress 30 

3 



CONTENTS. 



Page. 

Design and operation of pole-treating plants 30 

Experimental plants 30 

Commercial plant for butt treatments 31 

Cost of operation 32 

Design of plant for treatment of the entire pole 33 

Cost of pole treatments 34 

Tank treatment with creosote 34 

Tank treatment with zinc chlorid " 34 

Tank treatment with crude petroleum 35 

Brush treatment 35 

Increased life afforded by preservative treatment 35 

Financial saving 36 

Relation of preservative treatments to pole specifications 38 

Growth and form of poles 38 

Summary 39 

Appendix. 

Report of inspection of experimental poles 41 

Discussion of results .' 44 

Southern white cedar poles 44 

Chestnut poles 45 

Irregularities in results 45 

Height of decay above ground line 45 

Deterioration shown by change of grades 46 

Analysis of preservatives used in the treatment of poles set in the Augusta- 
Savannah and Helena-Meldrin lines 46 

Preservative sold as Avenarius Carbolineum 47 

Preservative sold as S. P. F. Carbolineum 47 

Preservative sold as Spirittine 47 

Coal tar creosote 48 

Preservative sold as Imperial Wood Preservative 48 

Preservative sold as Creolin 48 

Detailed tables and curves showing rate of seasoning of poles 49 

Table 27. — Rate of seasoning of southern white cedar poles at Wilmington, 

N. C 49 

Table 28. — Rateof seasoning of chestnut poles at Pisgah, N. C 50 

Table 29. — Rate of seasoning of chestnut poles at Dover, N.J 50 

Table 30. — Rate of seasoning of chestnut poles at Thorndale, Pa 51 

Table 31. — Rate of seasoning of chestnut poles at Parkton, Md 51 

Table 32. — Rate of seasoning of northern white cedar poles at Escanaba, 

Mich 52 

Table 33. — Rate of seasoning of western red cedar poles at Los Angeles, 

Cal 53 

Table 34. — Rate of seasoning of western yellow pine poles at Northfork, 

Madera County, Cal 54 



ILLUSTRATIONS. 



Plate I. Fig. 1. — Treating southern white cedar by -brush method. Fig. 2. — 

Treating chestnut poles by open-tank method 16 

II. Fig. 1. — Untreated pole of southern white cedar. Fig. 2. — Creosoted 

loblolly pine pole after eighteen years' service 24 

III. Fig. 1 — Cross section of the butt of a treated western red cedar pole. 

Fig. 2. — Cross section of the butt of a treated yellow pine pole 24 

IV. Cross section of a small loblolly pine pole treated with creosote 28 

TEXT FIGURES. 

Fig. 1. Progress of decay in an untreated pole 12 

2. An S iron driven in the butt of a pole _ 13 

3. Open tank and gin pole used in experimental pole treatments 31 

4. Plan of a commercial plant for the butt treatment of poles 32 

5. Plan of a commercial plant where the entire pole is to be treated 32 

6. Diagram showing condition of experimental poles 42 

7. Rate of seasoning of southern white cedar poles, Wilmington, N. C. . . 49 

8. Rate of seasoning of chestnut poles, Parkton, Md 52 

9. Rate of seasoning of northern white cedar poles, Escanaba, Mich 52 

10. Rate of seasoning of western red cedar poles, Los Angeles, Cal 53 

11. Rate of seasoning of western yellow pine poles, Madera County, Cal. . . 55 

5 



PRESERVATIVE TREATMENT OF POLES. 



INTRODUCTION. 

Users of poles in all parts of the country are alive to the necessity 
of obtaining increased length of service from their poles. This 
interest has been stimulated by the tendency toward advancing 
prices of forest products and apprehension with regard to the future 
supply. Realizing the need for more information along this line, the 
Forest Service a number of years ago began investigations of meth- 
ods for prolonging the life of poles, and during the past four years a 
number of circulars a giving the progress of experiments have been 
published. 

This bulletin aims to sum up the results that have already been 
published, and to present additional data and information, gained by 
the more recent investigations. 

GENERAL PRINCIPLES OF WOOD PRESERVATIONS 

Except in very warm and moist climates, a pole which is placed on 
skids and allowed to become air dry does not decay, because it does not 
contain sufficient moisture to support the growth of fungi and wood- 
boring insects, which are the causes of decay. However, if the pole is 
set, that portion of it in contact with the soil will absorb moisture 
until conditions favorable to decay are restored. To prevent decay 
in timber exposed to the soil or moist air, the wood substance, which 

a The Bureau of Entomology also has published results of investigations of damage 
to forest products by insects, in which it is shown that injury to pole timber and the 
commercial and utilized product by wood-boring insects contributes to direct deteri- 
oration and subsequent decay, and that much of this loss can be prevented by proper 
methods of management and treatment with preservatives. Attention is called to 
the following publications: Insect Injuries to Forest Products, by A. D. Hopkins, 
Bureau of Entomology, Yearbook, Department of Agriculture, 1904, pp. 381 to 398. 
Bulletin 58, Part V, Some Insects Injurious to Forests, Insect Depredations in North 
American Forests and Practical Methods of Prevention and Control , by A . D. Hopkins, 
in charge of Forest Insect Investigations, December, 1909, pp. 64 to 67, 79 to 81, and 
84. Bulletin 94, Part I, Damage to Chestnut Telephone and Telegraph Poles by 
Wood-boring Insects, by Thos. E. Snyder, Agent and Expert, Bureau of Entomology. 

The references to insects in this bulletin are based to a large extent on information 
supplied by the Bureau of Entomology. 

b For a more complete discussion of this subject, see Forest Service Bulletin 78, 
"Wood Preservation in the United States." 

7 



8 PRESERVATIVE TREATMENT OF POLES. 

is the food of the decay-producing organisms, must be rendered inca- 
pable of supporting fungous growth. In commercial timber- treating 
practice this is accomplished by the injection of antiseptics. 

It is not usually practicable even with the best methods of treat- 
ment, except in the case of very porous woods, to impregnate the 
wood throughout. The value of the treatment consists largely in creat- 
ing an outer protective envelope around the untreated interior wood. 
The thickness necessary for this envelope to give efficient protection 
depends on the use to which the timber is to be put. In general, the 
antiseptic should penetrate deep enough to prevent exposure of the 
untreated wood by abrasion, checking, or other action. Since the 
liability of the protective zone to destruction from mechanical 
causes or by gradual volatilization of the oil is dependent on its 
thickness, or, in other words, on the quantity of preservative ab- 
sorbed and the depth of penetration, it is reasonable to assume that 
within certain limits the added life of the timber due to treatment 
with a given preservative will be in approximate ratio to the amount 
of penetration and absorption of the preservative. 

FOUEST SERVICE INVESTIGATIONS. 

Knowledge of the results of creosote treatment is based largely on 
treatments made by the pressure method, using from 8 to 12 pounds 
or more of creosote to the cubic foot of timber. In spite of the 
excellent results that have been obtained by such treatment, it has 
been but little used by pole consumers, except in certain parts of the 
South, where exceptionally rapid dec a}'' makes preservative treat- 
ment imperative. The chief hindrances to a more general adoption 
of creosote treatment for poles have been the high cost of the treat- 
ment and the expense of transporting the timber to a distant point 
for treating. The investigations of the Forest Service. have, there- 
fore, been concerned mostly with cheaper and simpler methods, and 
with treatments winch could be applied locally without the erection 
of elaborate and expensive plants. Much attention has been given 
to the seasoning of poles, since proper seasoning not only prepares 
poles to receive the preservative treatment, but, under certain con- 
ditions, may be in itself a means of increasing their durability. The 
treating investigations proper have followed three general lines: 

(1 ) Testing the efficiency of various wood preservatives and of 
applications of varying amounts, 

(2) The developing of a method for impregnating the portion of a 
pole most subject to decay — the butt. 

(3) Designing of inexpensive apparatus suited to the treatment of 
poles in small quantities, or in such quantities as local needs may 
require. 



KESTJME OF PEOJECTS. 9 

In these investigations much assistance has been received from a 
number of electrical companies, which have placed poles at the dis- 
posal of the Forest Service for the tests and contributed funds toward 
paying the cost of the investigations. The experimental poles, in 
most instances, have been placed in service by the companies inter- 
ested, and in such a manner that durability records may be obtained 
from them. These records will prove a source of further information 
on the efficiency of the treatments. 

RESUME OF PROJECTS. 

In 1902 field investigations were begun in cooperation with the 
American Telephone and Telegraph Company. The project as finally 
developed included chestnut, southern white cedar, and northern 
white cedar a poles, experiments with the first being conducted in 
North Carolina, New Jersey, Pennsylvania, and Maryland, with the 
second in North Carolina, and with the third in Michigan. Another 
project undertaken in cooperation with a number of pole-using com- 
panies in California, 6 included a study of the treatment of western 
yellow pine and western red cedar poles. Further sources of the 
information were afforded by treatments of lodgepole pine poles at 
a plant erected by the Forest Service on the Sopris National Forest 
at Norrie, Colo., and of loblolly pine poles at a plant designed by the 
Forest Service and erected by the North Louisiana Telephone Com- 
pany at Winnfield, La. In addition to the tests in seasoning and 
treating, a number of experimental pole lines have been set, in which 
poles treated with various preservatives have been placed alongside 
of untreated ones in order that their durability might be compared. 

a This tree ( Thuja occidentalis) has in earlier publications of the Forest Service been 
referred to under the common name of arborvitse. It is, however, usually known by 
lumbermen and woodsmen generally as "white cedar." The name "white cedar" 
has in Forest Service publications been used to designate Chamsecyparis thyoides, which 
is also most widely known as "white cedar." This latter tree, though sometimes found 
as far north as southern Maine, is of commercial importance chiefly south of Delaware 
and New Jersey. Thuja occidentalis, common in the northern woods of New England, 
New York, and the Lake States, occurs as far south as North Carolina and Tennessee, 
but only in the mountains where the elevation is sufficiently great to permit northern 
species to thrive. To distinguish these two species without doing violence to ordinary 
usage, Thuja occidentalis, or "arborvitse," will in the present bulletin receive the name 
of northern white cedar, and Chamsecyparis thyoides the name of southern white cedar. 
The western species, Thuja plicata, formerly designated in Forest Service publications 
as "giant arborvitse," and most commonly known in the West as red cedar, will be 
called in the present bulletin western red cedar. 

b The following companies contributed to the support of that project: Edison Elec- 
tric Company, Home Telephone Company, Los Angeles Gas and Electric Company, 
Los Angeles-Pacific Kailway Company, Pacific Electric Company, Pacific Gas and 
Electric Company, Pacific Light and Power Company, and San Joaquin Light and 
Power Company. 

72742°— Bull. 84—11—2 



10 



PRESERVATIVE TREATMENT OF POLES. 



RESULTS OF SEASONING TESTS. 
LOSS OF WEIGHT. 

Table 1 shows in round numbers the weight lost by poles during 
seasoning until approximately air-dry. After the weights shown in 
this table have been reached, loss of moisture does not cease, but may 
continue at a decreasing rate for many months. 

Table 1. — Weight lost during seasoning of poles until approximately air-dry. 



Species. 


Dura- 
tion of 
season- 
ing. 


Green 

weight 

per cubic 

foot. 


"Seasoned 

weight 

per cubic 

foot. 


Green 

weight 

lost. 


Total 
weight 

lost 
per pole. 


Nominal size of 
poles. 


Average 
volume 
of poles. 


Diame- 
ter. 


Length. 




Months. 
4- 8 
3- 8 
6-12 
3- 5 


Pounds. 

56 

a 37 

33 

6 33 

65 


Pounds. 
47 
26 
25 
25 
33 


Per cent. 
16 
30 

24 
24 
49 


Pounds. 
180 
228 
141 
219 
835 


Inches. 
7 
7 
7 
8 
8 


Feet. 
30 
30 
30 
40 
40 


Cubicfeet. 
20.00 


Southern white cedar 

Northern white cedar 


20.76 
17.62 
27.34 


Western yellow pine 


3- 9 


26.10 



a Weight on arriving at Wilmington, N. C, after rafting down the river. 

& Approximate weight on arriving at southern California ports after transportation by boat from Puget 
Sound. Some of the shipments weighed more. 

The limits of seasoning given in Table 1 are such as would be 
feasible in commercial practice, and indicate the weight poles must 
reach in order that the main bulk of the water which may be gotten 
rid of by air seasoning shall be evaporated. This means a loss ordi- 
narily of from 16 to 30 per cent of the original weight, amounting to 
from 141 to 228 pounds per pole in these tests, and for western 
yellow pine the enormous loss of 49 per cent, or 835 pounds per pole, 
occurred. Table 2 illustrates the saving in transportation charges 
possible through pole seasoning. 

Table 2. — Saving in freight charges effected by seasoning of poles. a 



Species. 



Seasoned 
poles re- 
quired for 
minimum 
carload of 

40,000 
pounds. 



Total de- 
crease in 
weight 
due to 
seasoning. 



Saving in freight 
on carload lots. 



25-cent 
rate. 



15-cent 
rate. 



Chestnut 

Southern white cedar 
Northern white cedar 

Western red cedar 

Western yellow pine . 



Number. 



Pounds. 
7,700 
16, 900 
12, 800 
12,900 
38,400 



Dollars. 
19.25 
42.25 
32.00 
32.25 
96.00 



Dollars. 
11.55 
25.35 
19.20 
19.35 
57.60 



o Based on sizes and weights of poles given in Table 1. 



RESULTS OF SEASONING TESTS. 



11 



RATE OF SEASONING. 

The rate at which wood seasons is dependent on many factors, most 
important of which are climatic and seasonal conditions. Two poles 
of the same species and in the same locality, but cut at different 
times of the year, will require different periods of time to lose equal 
amounts of moisture. Table 3 shows in detail the time required for 
poles cut at different seasons of the year to reach the degree of dryness 
given in Table 1 . 

Table 3. — Time required for poles cut at different periods of the year to season to approxi- 
mately air-dry weight. 





Location of test. 


Time required for seasoning. 


Species. 


Spring- 
cut. 


Summer- 
cut. 


Autumn- 
cut. 


Winter- 
cut. 






Months. 

5 

3 

■ 12 

f a& 4 

\ c (3) 

S 


Months. 
4 • 
3 
9 
a5 
c(6) 
3 


Months. 
8 
8 
7 
i3 
c(7) 
9 


Months. 
7 






5 






6 




Wilmington, Cal 


a3 






c(4) 
6 









a Period of seasoning computed from time poles arrived at Wilmington three to seven months after 
cutting. 
b Weight of spring-cut poles at termination of test, 28 pounds per cubic foot, 
c Period in storage and in transit, during which time little seasoning took place. 

Poles cut during the spring and summer dry rapidly and, except 
in the case of white cedar in the latitude of northern Michigan, 
reach an approximately air-dry condition before the following winter. 
White cedar poles cut during the spring and summer did not become 
air-dry until the following year, and required more time than poles 
cut during the autumn and winter to reach an equal degree of dry- 
ness, the autumn-cut and winter-cut poles becoming dry by the fol- 
lowing summer. However, during the early part of this experiment 
the poles lay on skids in the woods, where seasoning was retarded by 
lack of air circulation and sunshine, and by the swampy character 
of the soil. In February all poles, consisting of monthly cuts from 
April to December, inclusive, were removed to the Escanaba yard, 
where conditions were much more favorable to rapid seasoning. 

The irregularity in the results of the western red cedar tests was 
caused by the long period the poles were in storage (in water) and in 
transit, piled solidly on the decks of vessels, little seasoning taking 
place during this period. 



FACTORS AFFECTING SEASONING. 



The effect of the climatic conditions of different seasons of the year 
and of various regions in which the tests were made has already been 
brought out in Table 3, and is more fully shown in the detailed season- 



12 



PRESERVATIVE TREATMENT OF POLES. 



ing tables and curves in the Appendix. Besides climatic and seasonal 
conditions, many other factors affect the rate of drying out of poles, 
among which are the following: 

(1) Method of piling. — In the tests the poles were spread out in 
single layers on skids, in which form seasoning is most rapid. Season- 
ing will be much retarded if the poles are stacked in solid piles, and 
if that form of pile is used in a warm, moist climate, decay or injury 
by wood-boring insects is likely to follow should the poles be held for 
any considerable period. 

(2) Exposure. — Seasoning is hastened by having the poles exposed 
to a free circulation of air. An open place free from underbrush or 
other rank growth should be chosen for the skidways. Shade does not 

seem to retard the loss of 
moisture, provided the circu- 
lation of air is not impeded. 
(3) Soaking. — Poles that 
were soaked from two to four 
weeks in water dried out very 
rapidly and in a compara- 
tively short time reached 
the same degree of dryness 
as other poles cut at the 
same time and not soaked. 
Thereafter the seasoning of 
both proceeded at practi- 
cally the same rate. 

CHECKING. 

Fig. 1.— The shaded areas show progress of decay in an While rapid Seasoning 

untreated pole. Seasoning checks, by increasing the k : f noss ibla to realize 

amount of surface exposed, may hasten decay. maKes ll pObSlDie LO ie<mze 

the benefits of reduced trans- 
portation costs most quickly, it may be harmful in its effect on the 
timber itself. Poles seasoned rapidly check more than those seasoned 
slowly. Timber which seasons slowly and evenly forms numerous 
small checks, which close again when the wood absorbs moisture 
and which apparently have no detrimental effect. If, however, the 
poles season rapidly, wide and deep checks may be formed, which 
do not again close, and which not only decrease the strength of the 
timber, but materially hasten decay through the entrance of insects 
and fungi. Figure 1 shows the detrimental effect of checks that 
expose a very large surface to decay; they increase the rate of dete- 
rioration. Splits, windshake, and other defects of this character have 
a similar influence on the durability of the poles when the defects 
occur near the ground line. 




BRUSH METHOD. 



13 



Some species of wood, notably chestnut, have a tendency to 
form large checks or splits ; in some cases the split opened a foot wide 
and extended 9 feet upward on the pole. By the use of S irons at 
the first indication of a tendency to such checking, serious damage 
may be avoided. These may be made of strap iron one-eighth inch 
by 1 inch, bent in the form of a letter S, from 3 to 6 inches long, 
and driven into the butt of the pole as shown in figure 2. 

SHRINKAGE. 

Hundreds of careful measurements show that the amount of 
shrinkage which takes place during the seasoning of poles is very 
slight, though this is contrary to the opinion of pole producers and 
consumers. The "amount of shrinkage in seasoning from green to air- 
dry condition averaged from 
0.3 to 0.5 per cent on the 
circumference at the ground 
line (6 feet from the butt), 
and from 0.6 to almost 1 
per cent at the top. On 
the sizes of poles more com- 
monly used this is equiva- 
lnet to about 0.1 or 0.2 of 
an inch in the circumference 
of the butt and from 0.15 
to 0.25 of an inch on the top. 

BRUSH METHOD OF TREAT- 
ING POLES. 




Fig. 2. — An S iron driven into butt of pole to prevent the 
opening of seasoning checks. 



A very simple method of 
using a preservative consists 
in applying it to the surface 
of the wood with a brush. There " are several patented or pro- 
prietary preservatives intended for use in this manner. While the 
experiments show good results from surface applications of anti- 
septic oils, this form of treatment does not present a complete solution 
of the question of pole preservation. 

A brush method of treatment has the advantage of very low cost, 
owing to the small amount of preservative used and to the fact that 
no special treating apparatus is required. It is especially useful 
where the number of poles is small, or the region remote, so that the 
erection of even the most simple form of treating plant would not be 
justified. In the experiments, a penetration of from one-eighth to 
one-fourth inch was obtained in seasoned timber. Table 4 shows the 
amounts of preservative absorbed in a number of tests. The absorp- 
tion was ascertained by weighing the vessel containing the preserva- 



14 



PRESERVATIVE TREATMENT OF POLES. 



tive before and after each treatment, the difference in weight being 
taken as the amount absorbed by the pole. In all cases the pre- 
servative was applied hot. a 
Table 4. — Average absorption of creosote resulting from the brush method of treatment. 



Species. 


Locality. 


Absorption per pole. 


Length 
of pole. 


Length 
treated. 


Number 
of poles 
averaged. 


1 coat. 


2 coats. 






Pounds. 
2.6 


Pounds. 
4.7 
4.9 
4.4 
6.5 

3.6 


Feet. 
30 
30 
30 
40 

40 


Feet. 
a6 
a6 
a6 
68 

67 


92 






50 






3.0 


98 




Los Angeles and Wilming- 
ton, Cal. 
Pollasky, Cal 


75 


Western yellow pine . . . 


2.4 


32 







a Between 2-foot and 8-foot points on butt. 



b From butt to height indicated. 



Much care should be exercised to fill or coat all season checks with 
the preservative, for unless this is done the treatment is likely to 
prove ineffective, because decay will get a foothold in these checks. 
Only poles which are thoroughly seasoned should be treated and the 
preservative should not be applied when the surface of the wood is 
wet, as after a rain, or when very cold. In most cases, better results 
will be obtained by heating the preservative before applying. Bits 
of bark adhering to the poles should be carefully removed. While 
this is necessary in all treatments, it is especially important in brush 
treatments. Even if the treatment is apparently well done, decay 
may get a start in the untreated portion underneath the protecting 
layer of treated wood. 

OPEN-TANK PROCESS OF TREATING POLES. 

The open-tank process of timber treating, the principle of which 
has been described in another publication, 6 consists in subjecting the 
timber to successive baths of hot and cold preservatives. In this 
way atmospheric pressure is used to accomplish to a large extent 
what is more commonly accomplished by artificial pressure. The 
open-tank or nonpressure method, like the brush method already 
described, has the advantage that the preservative may be applied 
to the butt of the pole only, and this avoids the expense of applying 
it to the portion above ground, which in many cases is sufficiently 
durable without treatment. The efficiency of the method as regards 
the first object of treatment, the impregnation of the wood, is shown 
in Table. 5. These figures represent typical results obtained in the 
treatments. 

a As a rough approximation of the quantity of preservative required for pole treat- 
ments, 1 gallon may be allowed for each 25 square feet of surface to be covered, when 
two coats are applied. 

& Forest Service Bulletin 78, "Wood Preservation in the United States," by W. F. 
Sherfesee. 



OPEN-TANK PROCESS. 



15 



Table 5. — Average absorption and penetration of creosote obtained in the butt treatment 
of poles by the open-tank method. 



Species. 


Absorp- 
tion per 
pole. 


Penetra- 
tion. 


Species. 


Absorp- 
tion per 
pole. 


Penetra- 
tion. 




Pounds. 
21.5 
48.4 
39.5 


Inches. 
0.3 
.5 
.8 


Western yellow pine 


Pounds. 
81.4 
34.0 


Inches. 
3.1 




1.0 


Western red cedar 







MANNER OF APPLICATION. 

In the open-tank process the impregnation is accomplished by 
subjecting the timber to a change in temperature, by means of a hot 
followed by a cooler bath. Any one of three general methods may 
be followed to accomplish this result: (1) After the timber has been 
held in the hot preservative for the required length of time, the heat- 
ing may cease and without other change the whole be allowed to cool; 
(2) the timber may be transferred from the hot liquid to another tank 
containing cooler preservative; (3) the preservative may be changed, 
the hot being drawn off and colder preservative run into the treating 
tank. The three methods of procedure indicate in a general way the 
different types of apparatus which may be used in the treatments. 

DURATION OF TREATMENT. 

Many of the experimental treatments were made with long treating 
periods in order to determine the maximum amount of penetration 
.or absorption possible, and in some cases further tests showed that 
very much shorter periods of treatment gave as good or nearly as 
good results as the long treatments. While it is desirable, in com- 
mercial practice, to give the treatment in the shortest time possible, 
the fact should not be overlooked that the open-tank process of 
treatment is an impregnation process, and differs radically from a 
mere dipping process, or a coating of the surface with preservatives. 
It is therefore not advisable to reduce the length of the treatment to 
such an extent as to risk impairing its efficiency. 

The time necessary to secure any desired penetration or absorption 
will vary with the species, the moisture condition of the timber, and 
many other factors, and must be determined by actual test in each 
case. Some species have a comparatively narrow sapwood, and a 
heartwood which it is difficult or impossible to penetrate; with such 
species it is useless to prolong the treatment after the sapwood has 
been penetrated. Other species, among which are loblolly and 
western yellow pines, have wide sapwood and treat very easily, and 
with these it is necessary to regulate the treating period so as to 
avoid an unnecessarily large absorption of the preservative. 



16 PRESERVATIVE TREATMENT OP POLES. 

Except in the case of very dry and porous woods, the absorption 
takes place mostly during the cooling process. The function of the 
hot bath is to prepare the wood for treatment. The drier the wood, 
the shorter the period of the hot bath needed. A long period in the 
cold bath, allowing the preservative to cool to atmospheric tempera- 
ture, gives a saturated absorption. Shortening the cold bath and 
removing the timber while the preservative is still fairly hot gives a 
relatively deep penetration as compared with the quantity of pre- 
servative absorbed. This consideration is of especial value in treating 
porous wood. 

TEMPERATURE OF HOT BATH. 

In most of the experiments the hot bath was given at a tempera- 
ture slightly above the boiling point of water, that is, from 215° to 
230° F. There are a number of advantages in using a high tem- 
perature, and it is especially necessary if timber is not thoroughly 
air-dry. However, a number of successful treatments were made 
with temperatures of 200° and less. Further tests should be made 
to determine the lowest efficient hot-bath temperature for the treat- 
ment of seasoned poles. In order that volatilization of creosote may 
be reduced to a minimum, it is desirable that the hot bath be given 
at as low a temperature as possible without impairing the efficiency 
of the treatment. 

INFLUENCE OF RATE OF GROWTH. 

Among trees of the same species, those having wide annual rings 
commonly have wider sapwood than those whose growth has been 
less rapid, and since in many species it is only the sapwood that is 
penetrated, it follows that the pole of rapid growth will absorb more 
preservative than the one of slow growth. Chestnut poles showing 
a maximum growth of 2 rings to the inch absorbed the preservative 
to a depth of 0.75 of an inch, while others having 15 annual rings 
to the inch received a penetration of only 0.2 of an inch. The pene- 
tration in the case of northern white cedar poles averaged 0.6 of an 
inch for poles with less than 20 rings to the inch and 0.4 of an inch 
for those having more than 40 rings to the inch. 

It is probable that the variation in wood structure due to difference 
in rate of growth, aside from the relative amounts of heartwood and 
sapwood, affects the absorption and penetration of preservative, but 
there is no conclusive evidence on this point. 

INFLUENCE OF MOISTURE. 

In general, the drier the wood the more readily it may be treated. 
Poles thoroughly air-seasoned require less time for treatment than 
those only partially seasoned. The treatment of green timber is 



Bui. 84, Forest Service, U. S. Dept. of Agriculture. 



Plate I. 




Fig. 1.— Treating White Cedar by Brush Method. 




Fig. 2.— Treating Chestnut Poles by Open-Tank Method. 



ADVANTAGES AND LIMITATIONS. 17 

unsatisfactory because of the small absorption and irregular penetra- 
tion of the preservative. Another important reason why unseasoned 
poles should not be treated is that such poles are likely to check in 
drying, and thus expose untreated wood to decay. 

INFLUENCE OF SEASON OF CUTTING. 

In the experiments with western yellow pine, poles cut in different 
seasons of the year differed greatly in the ease with which they 
absorbed the preservative, the summer-cut poles absorbing less than 
those cut at any other season. This difference in absorptive qualities 
may have been due to rate of seasoning and rate and conditions of 
growth, rather than to inherent differences in the wood due to the 
time of cutting. It is known that absorption may be retarded by 
"case hardening" that may result from too rapid drying. Tests on 
chestnut show that poles having the same moisture content, although 
they were cut at different periods of the year, absorb the same quan- 
tities of preservative. 

INFLUENCE OF SOAKING IN WATER. 

Chestnut poles which had been soaked in water two weeks and 
then seasoned did not absorb any more creosote than poles that had 
not been soaked. . Soaking in water is rarely justified as a means of 
making wood more permeable to preservatives. 

ADVANTAGES AND LIMITATIONS OF THE OPEN-TANK PROCESS. 

The tests made by the Forest Service indicate that the sap^vood 
of a great variety of species, including nearly all of our common 
native woods, when seasoned can be successfully impregnated by the 
open-tank process. The heartwood of many species offers consider- 
able resistance to impregnation and can not be so well treated without 
pressure. However, with the exception of a few species having an 
unusually narrow sapwood, it is believed that the thorough treat- 
ment of the sapwood portion of round timber will afford good pro- 
tection to the entire stick. Since poles are almost always used in 
the round, the open-tank process is especially well adapted to the 
treatment of this class of timber. The apparatus required is com- 
paratively simple and inexpensive, especially where but few poles 
are to be handled, and if desired can be made portable. 

The open-tank process is not adapted to the treatment of woods 
which are difficult to impregnate, nor to unseasoned or partially 
seasoned wood, and as regards economy of operation has not justified 
itself in plants designed for the treatment of the entire pole. The 
large amount of oil lost by volatilization from open tanks and the 
difficulty of accurately gaging and regulating the amount absorbed 
are other disadvantages. 

72742°— Bull. 84—11 3 



18 PKESERVATIVE TREATMENT OP POLES. 

RESULTS OF TREATMENTS, BY SPECIES. 
CHESTNUT. 

Chestnut is widely distributed throughout the entire Appalachian 
mountain region and is extensively cut for poles, ranking next to the 
cedars in the quantity used. The reported number of chestnut poles 
purchased in 1909 was 608,000.° Chestnut is durable, and the esti- 
mated average length of life of an untreated pole is from 10 to 12 
years. The sapwood is very narrow, usually from about one-eighth 
to three-eighths of an inch wide. The heartwood of chestnut, like 
that of many other species, is difficult to impregnate with preserva- 
tives, and the penetration secured in the treatment is comparatively 
small. This fact, however, does not constitute a valid reason for not 
giving the wood such treatment as is possible. While the absorp- 
tion of the small amount of preservative and the small penetration 
can not be expected to prolong the life of the timber to the same 
extent as would a greater absorption and depth of penetration, the 
increased life secured will undoubtedly more than pay for the cost of 
the treatment. 

A large number of tests were made in the seasoning of chestnut 
poles, and the rate of seasoning was determined for a number of 
localities. Poles cut near Parkton, Md., and having an average green 
weight of 56 pounds per cubic foot, reached a weight of 47 pounds in 
from 4 to 8 months, depending upon the time of cutting. The fall 
and winter cut poles of the same lot, at the end of 12 and 9 months, 
respectively, had reached a weight of 45 pounds, and winter-cut 
poles at Thorndale, Pa., weighing 53 pounds per cubic foot to begin 
with, dropped to 42 pounds in 11 months, remaining practically sta- 
tionary in weight at that point. 

Brush Treatments. — Brush treatments were made in each of the 
tests with chestnut poles. As an example of the results obtained 
and because these poles will be referred to again in this bulletin, 6 the 
treatments made at Pisgah, N. C, are given in detail in Table 7. The 
poles were treated for a distance of 6 feet, beginning 2 feet from the 
butt. 

a Bureau of the Census: " Poles Purchased, 1909." 

b Appendix, "Report on Inspection of Experimental Poles. ■ ' 



EESULTS OF TREATMENTS. 



19 



Table 7. — Amount of preservative absorbed in the brush treatment of chestnut poles at 

Pisgah, N. C. 



Preservative sold as — 


Number 
of coats. 


Absorption per pole. 


Average. 


Maximum. 


Minimum. 




2 
1 
2 
1 
3 
2 
3 
1 
2 
2 
1 


Pounds. 
4.1 
3.7 
4.2 
3.2 
6.7 
7.0 
6.5 
5.1 
5.4 
6.4 
7.0 


Pounds. 
5.1 
4.6 
5.5 
3.9 
9.0 
10.6 
8.3 
5.5 
7.0 
8.4 


Pounds. 
2.9 




2.4 




3.1 




2.5 




4.9 




4.3 




3.8 




4.6 




3.8 




4.5 


Tar 











The thin sapwood of chestnut has a tendency to scale off after the 
pole has been exposed for some time to the weather. An inspection 
of brush-treated chestnut poles shows that in certain cases the failure 
of the treatment was due to this cause. Possibly better results would 
be secured from brush treatments if the sapwood were shaved off for 
a few feet above and below the ground line, so that the preservative 
would be applied to the more firm heartwood. 

Tank Treatments. — Table 8 shows the results of the treatment of 
chestnut poles at Parkton, Md., with creosote, by the open-tank proc- 
ess. Treatments at Dover, N. J., and Thorndale, Pa., gave somewhat 
similar results. 

Table 8. — Absorption and penetration of creosote in the open-tank treatment of chestnut 

poles, Parkton, Md. 



Treatment. 


Number 

of rings 

in outer 

inch. 


Average 
penetra- 
tion. 


Average 
absorp- 
tion. 


Basis 
poles. 


Hot oil. 


Cooling 
oil. 


Cold 

oil. 


Tempera- 
ture of 
hot oil. 


Hours. 
10 
8 
6 
4 
6 
4 


Hours. 
14 
14 
14 
14 


Hours, 


"F. 
228 
223 
225 
225 
229 
231 


10 
10 
8 
8 
9 
7 


Inch. 
0.30 
.29 
.34 
.33 
.34 
.38 


Pounds. 
20.7 
21.3 
23.6 
20.9 
21.3 
20.6 


Number. 
16 
8 
24 
24 
24 
16 








2 
2 







It appears from this table that four hours in hot oil gives nearly 
as good a treatment as a longer period and that by changing the 
poles to the tank containing cold oil as good results are obtained 
in two hours as by leaving the poles in cooling oil overnight. The 
penetration in all cases was small, averaging from 0.3 to 0.4 of an 
inch. No tests were made with shorter periods of treatment, but 
it is probable that for practical purposes an efficient treatment can 
be given well-seasoned chestnut poles in a somewhat shorter period 



20 



PEESEEVATIVE TBEATMENT OF POLES. 



than six hours. Poles with wide annual rings and wide sap wood 
absorbed more oil and showed a deeper penetration than those having 
a slower growth and narrower sapwood.. 

SOTJTHEEN WHITE CEDAR. 

The white cedar of the South, or "juniper," as it commonly called 
by telephone men, is used locally to a considerable extent for poles. 
The woods known under the general name of "cedar" comprise a 
number of distinct species and differ in their durability, the white 
cedar of the southern swamps being somewhat less durable than 
the cedar of the Lake States. 

Pole-using companies reported 44,000 a southern white cedar poles 
purchased in 1909. The average life is assumed to be from ten to 
thirteen years, but in unfavorable situations a large proportion of the 
poles fail in a shorter period. The sapwood, which is usually from 
one-half to 1 inch wide, decays very quickly. The poles used in the 
southern white cedar experiments were cut in the swamps of North 
Carolina and rafted about 90 miles down the Cape Fear River to 
Wilmington, where they were placed on skidways and seasoned until 
they reached a weight of from 25 to 26 pounds per cubic foot. South- 
ern white cedar received brush treatments alone, and a number of 
different preservatives were used. As in the case of chestnut, a 
6-foot space was treated, between the 2-foot and 8-foot points at 
the base of the pole. The results are summarized in Table 9. 

Table 9. — Amount of preservative absorbed in the brush treatment of southern white 
cedar a at Wilmington, N. C. 



Preservative sold as — 



Number 
of coats. 



Absorption per pole. 



Average. Maximum. Minimum 



Avenarius Carbolineum 

S. P. F. Carbolineum 

Do 

Spirittine 

Creosote 

Do 

Imperial Wood Preservative 

Creolin ■ 

Tar 



Pounds. 
3.6 
3.7 
1.6 

4.7 
4.9 
7.1 
4.4 
6.0 
7.0 



Pounds. 
4.7 
5.3 
1.6 
5.5 
6.4 
8.0 
5.3 
7.4 



Pounds. 
2.6 
2.8 
1.6 
4.1 
3.3 
5.6 
3.4 
4.5 



a These poles were included in the experimental line set near Savannah, Ga., a report on the inspection 
of which is given in the Appendix. 

NORTHERN WHITE CEDAR. 

This species is very commonly used for poles throughout the cen- 
tral and eastern portion of the United States, and, together with 
smaller quantities of chestnut and oak, is the main source of supply 



a Bureau of the Census: " Poles Purchased, 1909." 



KESULTS OF TREATMENTS. 



21 



for these regions. Of the three and three-fourths million poles pur- 
chased in 1909 by telephone, telegraph, electric power, and steam 
railway companies, two and four-tenths millions, or about two-thirds, 
were cedar. a While the statistics do not separate the northern 
white cedar from other timbers known commercially as cedar, it is 
certain that by far the greater number are of this species, the principal 
source of supply of which is in the States bordering the Great Lakes. 
It makes a very desirable pole, since it lasts from twelve to fifteen 
years untreated. Northern white cedar is a high-priced pole timber, 
however, and it will undoubtedly pay to apply preservative treatment 
to increase the durability of the poles and thus decrease the annual 
service charge. The treating experiments included brush treatments 
with creosote and with carbolineum, and open-tank treatment with 
creosote. The poles were seasoned until approximately air-dry and 
weighed 22^ pounds per cubic foot at the time of treatment. 

Brush Treatments. — The preservative was applied to the butts 
between the 2-foot and 8-foot points. 



Table 10. 



-Amount of 'preservative absorbed in the brush treatment of northern white 
Cedar poles, Escanaba, Mich. 



Preservative sold as — 


Number 
of poles 
averaged. 


Absorption. 


First 
coat. 


Second 
coat. 


Total. 


Carbolineum 

Creosote 


98 
98 


Pounds. 

. 2.4 

3.0 


Pounds. 
1.5 
1.4 


Pounds. 
3.9 
4.4 



The penetration of the preservative in these treatments did not 
average more than one-sixteenth of an inch. The work was done 
during the winter, and, although the preservative was heated to 
between 200° and 220° F., the low temperature of the timber and 
atmosphere caused it to thicken on the surface of the wood. Under 
more favorable conditions the penetration should be deeper. 

Tank Treatments. — Creosote tank treatments were made by 
heating the poles in the oil and maintaining the temperature at 
approximately 220° F. for from three to twelve hours and allowing 
them to cool in the oil overnight. A summary of the results is 
given in Table 1 1 . 

a Bureau of the Census: " Poles Purchased, 1909." 



22 



PEESERVATIVE TREATMENT OF POLES. 



Table 11. — Amount of preservative absorbed in the open-tank treatment of northern 
white cedar poles, Escanaba, Mich. 



Number 
of poles 
averaged. 


Duration of treatment. 


Absorp- 
tion per 
pole.. 


Hot oil. 


Cooling oil. 


34 
75 
43 


Hours. 

3 to 5 

6 

7 to 12 


Hours. 

Overnight 

do 

do 


Pounds. 
42 
49 
50 





There was considerable irregularity in the results on different 
poles in the same treatment, but the general tendency is well shown 
by grouping the treatments and thus averaging a greater number of 
poles, as in Table 11. Little practical advantage seems to be gained 
by prolonging the hot bath above three or four hours, although the 
absorption averages somewhat higher. The average penetration 
obtained in the treatment was approximately 0.5 inch, varying 
from 0.2 to 1 inch. The sapwood of the poles varied from 0.5 to 
1.0 inch in thickness. 

A very large proportion of northern white cedar poles have un- 
sound butts, 60 per cent of the experimental poles having defects 
more than 1 inch in diameter. In these tests, poles with sound 
butts absorbed, on an average, 11.1 pounds less than those with 
unsound butts. 

The treatments on northern white cedar were made with one 
tank only, which prevented a change from hot to cold oil. Tests 
with other species indicate that by a change of baths the results 
obtained by cooling overnight could have been accomplished in a 
few hours. 

WESTERN RED CEDAR. 



The light and durable western red cedar is much used for poles 
on the Pacific coast and throughout the Northwest. Also, it com- 
petes to a certain extent with northern white cedar in the East, its 
form and size making it especially desirable for the larger classes 
of poles. The principal points of production are northern Idaho 
and western Washington. The relative durability of western red 
and northern white cedar under similar conditions is not known, 
and the testimony by pole users on this point is somewhat contra- 
dictory. Experiments with western red cedar poles from the Puget 
Sound region were made at Wilmington and Los Angeles, Cal. 

Brush Treatments. — Brush treatments of creosote and car- 
bolineum were made, the preservative being applied to the butts 
of 40-foot poles to a height of 8 feet. The absorptions are shown 
in Table 12. 



RESULTS OF TREATMENTS. 



23 



Table 12. 



-Amount of preservative absorbed in the brush treatments of western red cedar 
(40-foot poles). 



CREOSOTE. 



Number 

poles 
averaged. 



Season cut. 



Summer . 

Fall 

Winter. . 
Spring... 



Weight 
per cubic 


Absorption per 


pole. 








foot of 
poles, a 


First 
coat. 


Second 
coat. 


Total. 


Pounds. 


Pounds. 


Pounds. 


Pounds. 


22 


00 


00 


12.4 


23 


00 


0) 


8.7 


24 


2.3 


1.5 


3.8 


28 


2.0 


1.5 


3.5 



SOLD AS CARBOLINEUM. 


12 
10 
10 
29 




22 
23 
24 
28 


0) 

0) 
2.6 
2.7 


0) 

0) 
2.1 
2.0 


10.3 
5.6 
4.7 
4.6 


Fall 









a Indicates stage of seasoning. 

b First and second coats not recorded separately. 

The absorption is relatively small when the preservative is applied 
.to comparatively unseasoned poles that weigh as much as 28 pounds 
per cubic foot and forms scarcely more than a coating on the surface. 
The increase in absorption is very slight until the weight falls below 
24 pounds, when it becomes rapid. At a weight of 22 pounds per 
cubic foot the absorption is two or three times as great as when the 
poles are in only a slightly greener stage. The penetration on the 
best seasoned poles averaged about one-eighth of an inch. Where 
the surface of the pole had become roughened by weathering, the 
penetration reached a maximum of one-half inch. 

Tank Treatment with Creosote. — In order to determine the 
maximum amount of creosote that could be injected, a number of 
treatments were made, keeping the poles in hot oil for periods ranging 
from one to six hours, at a temperature of between 220° and 230° F., 
and allowing them to cool overnight. For these treatments, summer 
and autumn cut poles were used, seasoned until they weighed, respec- 
tively, from 22 to 23^ and from 24 to 25 pounds per cubic foot. The 
absorption and penetration obtained are shown in Table 13. 



24 



PRESERVATIVE TREATMENT OP POLES. 



Table 13. — Absorption and penetration of creosote in the open-tank treatment of western 
red cedar poles' at Wilmington, Cal. 



Dura- 
tion of 
hot 
bath. 


Summer cut. 


Autumn-cut. 


35-foot poles, o- 


40-foot poles, a 


40-foot poles, a 


Poles 
aver- 
aged. 


Absorp- 
tion. 


Pene- 
tration. 


Poles 
aver- 
aged. 


Absorp- 
tion. 


Pene- 
tration. 


Poles 
aver- 
aged. 


Absorp- 
tion. 


Pene- 
tration. 


Hours. 
1 
2 
3 
4 
5 
6 


Number. 
24 


Pounds. 
36.5 


Inches. 
0.68 


Number. 


Pounds. 


Inches. 


Number. 


Pounds. 


Inches. 


23 


45.5 


0.90 


12 


33.0 


0.60 


33 
13 


34.0 
43.0 


.77 
.90 


12 

24 


46.0 
46.5 


.98 
1.00 


23 
24 


48.0 
43.0 


.65 
.62 


14 


31.0 


.SO 













^35-foot poles were treated to a height of approximately 6.5 feet and 40-foot poles approximately 7 feet. 
The average volume of the butt of a 40-foot pole is 6.5 cubic feet. 

These treatments represent complete or practically complete pene-. 
tration of the sapwood. Little or no penetration was obtained in the 
heartwood. The shorter periods of heating (with the long cooling 
periods) give nearly as good results as longer periods of heating. The 
effect of duration of treatment is more fully brought out in Table 14. 

Table 14. — Effect of duration of treatment on the absorption and penetration of creosote in 
the treatment of toestern red cedar poles. a 



Duration 
of hot 
bath. 


One hour cold bath. 


Two hours cold bath. 


Fifteen hours cooling. 


Poles 
aver- 
aged. 


Absorp- 
tion per 
pole. 


Pene- 
tration. 


Poles 
aver- 
aged. 


Absorp- 
tion per 
pole. 


Pene- 
tration. 


Poles 
aver- 
aged. 


Absorp- 
tion per 
pole. 


Pene- 
tration. 


Hours. 
1 
2 
3 
4 


Number. 


Pounds. 


Inches. 


Number. 


Pounds. 


Inches. 


Number. 

10 

6 

4 

5 


Pounds. 
27.0 
37.7 
41.0 
32.5 


Inches. 

0.58 

.65 

.60 

.47 


7 
5 
6 


25.6 
18.5 
26.0 


0.48 
.38 

.46 


6 


19.5 


0.35 


6 


23.8 


.01 



a Autumn-cut 40-foot poles seasoned to 23 pounds per cubic foot. 

It is seen from Table 14 that good treatments may be given in 
three hours ( two hours hot and one hour cold) , but that the results do 
not average quite as high as in some of the longer treatments. The 
six-hour treatments (four hours in hot oil and two in cold) seem to 
give as good penetration as cooling overnight, and to accomplish this 
with the absorption of a smaller quantity of oil. Because of the irreg- 
ularities in these results, the best period of treatment is not definitely 
determined, but it is believed that for very dry poles the short treat- 
ment will prove satisfactory, while if the timber is not so well seasoned 
it will be necessary to prolong the treatment. The effect of the degree 
of seasoning is illustrated in Table 15. 



Plate 




Bui. 84, Forest Service, U. S. Dept. of Agriculture. 



Plate III 




Fig. 1 .—Cross-Section of Western Red Cedar Pole Butt, 10 
Inches in Diameter, Showing Penetration of Creosote; Open- 
Tank Treatment. 




Fig. 2.— Cross-Section of Western Yellow Pine Pole Butt, 
14 Inches in Diameter, Showing Penetration of Creo- 
sote; Open-Tank Treatment. 



RESULTS OF TREATMENTS. 



25 



Table 15. — Effect of degree of seasoning on absorption and penetration of creosote in the 
treatment of western red cedar poles. a 



Time of cutting. 


Weight per 
cubic foot 

before 
treating. 


Absorption 
per pole. 


Penetra- 
tion. 


Poles 
averaged. 




Pounds. 
22-23J 
24-25 
28 


Pounds. 
45.2 
43.0 
28.4 


Inches. 
0.93 
.63 
.37 


Number. 
71 


Fall 


59 




26 







a Treatment consists of immersion from two to seven hours in hot oil and cooling overnight. 

While the poles used in obtaining these averages did not all have the 
same period of treatment, the same range of treatments applies to 
each of the several groups. Other treatments were made, the results 
of which do not exactly coincide with those here given, but notwith- 
standing the great variability in individual poles the table serves to 
illustrate the relative absorptive power of the poles in different stages 
of seasoning. 

Tank Treatment with Zinc Chlorid. — A number of treatments 
were made with zinc chlorid solution, mostly in long runs, keeping the 
bath at 212° F. for from four to seven hours and allowing the poles to 
cool in it overnight. The absorptions obtained are summarized in 
Table 16. 

Table 16. — Absorption of zinc chlorid solution in the treatment of western red cedar poles. 



Time of cutting. 


Weight per 
cubic foot 

before 
treating. 


Poles 
averaged. 

Number. 
8 

20 
90 


Duration of treatment. 


Average 
absorp- 


Hot bath. 


Cooling. 


tion per 
pole. 




Pounds. 
22J 
24" 
28 


Hours. 

5 

6 

4-7 


Hours. 

Overnight 

do 

do 


Pounds. 
61.5 




52 




45 









Table 16 illustrates the variation in amount of absorption of pre- 
servative solution obtained with poles in several stages of seasoning. 
A number of runs giving irregular results are not included in this 
table. Fall-cut poles seasoned to 23 pounds per cubic foot absorbed 
on an average only 30 pounds of solution per pole, and one lot of 
winter-cut poles seasoned to 25 pounds per cubic foot absorbed only 
21 pounds per pole, the poles all being given treatment of practically 
the same duration. As a rule, however, the absorption of zinc chlorid 
solution was slightly higher than that of creosote for the same period 
of treatment and increases, other things being equal, as the moisture 
content of the wood decreases. 

In a few treatments, the poles, instead of being left overnight in the 
cooling solution, were removed from the hot bath after from two to six 
hours and transferred to cold solution, in which they were left stand- 
72742°— Bull 84—11 4 



26 PRESERVATIVE TREATMENT OF POLES. 

ing from one-half to two hours. This method resulted in an average 
absorption of 28 pounds solution per pole. In the treatment of west- 
ern red cedar poles with zinc chlorid the aim should be to secure a 
complete saturation of the sapwood. The strength of the solution 
need not exceed 5 per cent. 

Other Treatments. — A few tests were made with crude petroleum, 
but very little penetration was obtained. Poles seasoned until they 
weigh 25 pounds or less per cubic foot may be given a combination 
creosote and zinc chlorid treatment by heating them in a creosote 
bath and then changing and allowing them to cool in the zinc chlorid, 
but poles first treated with zinc chlorid solution will take very little 
creosote if dipped into the oil while they are in a saturated condition. 
However, such poles may be allowed to dry out and may then be 
dipped into a tank of heavy oil, or receive a brush treatment. A treat- 
ment of this character ought to prevent to a large extent the leaching 
out of the zinc chlorid. 

WESTERN YELLOW PINE. 

Western yellow pine is used for poles to a limited extent in certain 
parts of the Southwest, where the high cost of more durable pole tim- 
bers makes it necessary to find a cheaper substitute. The life of this 
timber, untreated, is very short. In the upper part of the San Joaquin 
Valley of California, where a study of this species was made, untreated 
pine poles last only two or three years; but since the wood when not 
exposed to the soil is fairly durable, it is believed that a butt treatment 
with a good wood preservative will result in a pole that will give good 
service. A butt-treated pine pole costs considerably less than an 
untreated cedar pole in this locality. Fortunately, western yellow 
pine is a timber which takes treatment very readily, and no difficulty 
is encountered in securing any desired absorption if the poles are 
seasoned. 

Seasoning tests were made at Northfork, Madera County, Cal., 
where about 650 poles were cut, the cutting periods being distributed 
throughout the year. The green weight of the poles averaged slightly 
above 65 pounds per cubic foot, 40-foot poles averaging about 1,700 
pounds. The treatments were made when the poles had lost from 50 
to 55 per cent of their original weight, and weighed from 30 to 32 
pounds per cubic foot. From three to ten months were required to 
reach this degree of dryness. 

Brush Treatments. — Brush treatments were made with carbo- 
lineum and creosote, the preservative being applied to a height of 8 
feet on the pole butts. 



RESULTS OF TREATMENTS. 



27 



Table 17. — Amount of preservative absolved in the brush treatment of western yellow 

pine poles. 





Poles av- 
eraged. 


Absorption. 


Preservative sold as — 


First 
coat. 


Second 
coat. 


Total 




Number. 
27 
32 


Pounds. 
3.0 
2.4 


Pounds. 
1.8 
1.2 


Pounds. 
4.8 




3.6 







The penetration for creosote ranged from one-sixteenth to one- 
fourth of an inch, averaging about one-eighth of an inch, and for car- 
bolineum from one-sixteenth to one-half of an inch, with an average 
of about three-sixteenths of an inch. 

Tank Treatments with Creosote. — Tank treatments were made 
both by allowing the poles to cool in the hot-bath tank, and by trans- 
ferring them to a tank containing cooler oil. The results of a number 
of treatments by the former method are given in Table 18. 

Table 18. — Absorption and penetration of creosote in the open-tank treatment of 
western yellow pine poles. 



Poles 
averaged. 


Duration 
of hot 
bath. 


Maxi- 
mum 
temper- 
ature. 


Duration 
of cool- 
ing 
bath. 


Final 
heating 
temper- 
ature. 


Absorp- 
tion per 
pole, a 


Pene- 
tration. 


Number. 
42 
56 


Hours. 
3 
3 


°F. 
170-200 
170-200 


Hours. 
14 
14 


"F. 

200 


Pounds. 
81.4 
55.5 


Inches. 
3.1 
3.3 



a The average volume of the portion treated was 6.25 cubic feet. 

As shown in Table 18, three hours in hot oil and cooling overnight 
gave an average penetration of 3.1 inches, with an absorption of 81 
pounds of creosote per pole, or 13 pounds per cubic foot. Reheating 
after the same period of treatment resulted in approximately the 
same penetration, with a final absorption, however, of only about 
56 pounds per pole, or 9 pounds per cubic foot. A part of this 
difference may be accounted for by volatilization, which, while the» 
wood and oil are hot, is doubtless rapid enough to have some effect 
during the interval between the removal of the pole from the tank 
and the weighing. Nevertheless, there is a substantial saving in 
creosote by removing the poles from the oil while hot (after cooling 
10° or 20° from the maximum temperature), or by reheating the oil 
as in the case described. By this method the wood cells and cavities 
do not become supersaturated with .oil to the same extent as when 
the treatment is completed with the creosote at a low temperature. 

Very good results were also obtained by shorter treatment, both 
by allowing the poles to stand in the tank at the completion of the hot 



28 PRESERVATIVE TREATMENT OP POLES. 

bath until the temperature had fallen 20° or 30° F. or by transferring 
them to a tank containing cooler oil for a short period. 

Absorption is much influenced by rainfall and atmospheric condi- 
tions. During hot, dry weather heating the poles for an hour in the 
hot oil and dipping them a few minutes in the cold tank resulted in 
an absorption of 6 pounds of creosote per cubic foot and a penetration 
of 2 or 3 inches. At this time some of the poles absorbed a large 
amount during the hot bath, without the cooling process. In the 
cooler, rainier period before the dry weather set in, the hot bath 
resulted in an absorption of only 6 or 8 pounds of oil per pole. 

Tank Treatments with Zinc Chlorid. — Absorptions of zinc 
chlorid solutions average somewhat higher than creosote for the 
same periods of treatment. An average of about 18 pounds of 
solution per cubic foot a was obtained by giving the poles a hot bath 
of two or three hours, followed by cooling overnight. Standing the 
poles in cold solution for fifteen hours resulted in an absorption of 
nearly 10 pounds per cubic foot, and an absorption of 12 pounds to 
the cubic foot was obtained by a three-hour treatment, consisting of 
a hot bath followed by a change to cold solution. One-half a pound 
of dry zinc chlorid per cubic foot of timber is the amount commonly 
used in commercial practice for the treatment of crossties; that 
amount is approximated by using a 3 per cent solution for an absorp- 
tion of 16 to 18 pounds or a 4 per cent solution if the absorption is 12 
or 14 pounds to the cubic foot. Solutions varying in strength from 3 to 
10 per cent were used in the tests in order that the effect of various 
quantities of zinc chlorid on the durability of the wood may be 
determined by the durability of the poles in service in an experi- 
mental line. 

Tank Treatment with Creosote and Zinc Chlorid. — A treat- 
ment of both creosote and zinc chlorid may be given by using the 
former for the hot bath and the latter for the cold bath. The solution 
penetrates readily through the creosoted wood, the result being a 
pole with creosote in the exterior zone and zinc chlorid in the interior 
portion. It is, however, difficult to control the relative amounts of 
' creosote and solution absorbed, and if the poles are quite dry more 
than the desired amount of the former may be taken up during the 
heating process. 

Tank Treatments with Crude Petroleum. — Treatments with 
a heavy grade of crude petroleum were made, but impregnation is 
more difficult than with creosote. Two or three hours in hot oil, 
followed by cooling overnight, resulted in an average absorption of 
56 pounds per pole and a penetration of 2 inches. There is little 
definite knowledge, however, of the value of crude petroleum as a 
wood preservative. 

° The average volume of the portion treated was 6.25 cubic feet. 



Bui. 84, Forest Service, U. S. Dept. of Agriculture. 



Plate IV. 




Cross-Section of a Small Loblolly Pine Pole, Showing Penetration of Cre 




RESULTS OP TREATMENTS. 29 

LODGEPOLE PINE. 

Lodgepole pine grows at high altitudes in the Kocky Mountains, 
and is extensively cut for lumber, ties, and mine timbers, and to a 
limited extent for poles. Like the yellow pine, it decays quickly in 
contact with the soil, but is durable when not so exposed. The tree 
grows tall and straight, with very little taper, and makes a well- 
shaped pole. In certain parts of the West, where there are large 
bodies of fire-killed lodgepole that remain standing for many years, 
sound and throughly seasoned, conditions for effective treatment 
are excellent. If given a butt treatment, this dead timber makes a 
durable pole, and in many localities the cost of the pine pole plus the 
cost of the treatment is less than that of the Idaho cedar untreated. 
The sap wood of lodgepole pine, which on pole-size timber may be an 
inch or an inch and a quarter thick, is easily impregnated. In the 
treatments made by the Forest Service four hours were required to 
accomplish this result, hot and cold baths of about equal duration 
being used. About 35 pounds of oil were absorbed in the butt treat- 
ment of 30-foot poles. 

LOBLOLLY PINE. 

The pines are much used for poles in the South, but, with the excep- 
tion of the resinous heart of long-leaf pine, are not durable unless 
treated with preservatives. Loblolly pine because of its cheapness 
and ease of impregnation is very desirable if preservative treatment 
is contemplated. Moreover, its distribution, ease of reproduction, 
and rapidity of growth insure a steady and cheap supply. 

When this timber is used it is necessary to treat the entire pole 
instead of only the butt, as in case of the species previously discussed, 
especially in the warmer and more humid localities of the South. The 
pressure method has ordinarily been used at commercial plants, but 
good results are obtained in the treatment of loblolly and other sap 
pines without pressure, or with very light pressure. A nonpressure 
plant, designed by the Forest Service for the treatment of poles, was 
recently erected at Winnfield, La. A penetration of 2 inches in sea- 
soned poles may be obtained, with an absorption of from 8 to 12 
pounds of creosote per cubic foot. These results were obtained by 
treatments consisting of an initial hot bath, a short cold bath, and a 
final heating. From four to five hours are required for the treat- 
ment., which permits two runs per day, working one shift only. 
Plate IV shows a cross section of a pole which had received a treat- 
ment of 10 pounds per cubic foot and showed an average penetration 
of If inches. 



30 PRESERVATIVE TREATMENT OF POLES. 

CYPRESS. 

Cypress is usually considered a durable wood, and the heartwood 
is, in fact, one of the most durable of our native species. The sap- 
wood, however, decays quickly, and this seriously weakens the pole. 
The width of the sapwood on pole-size trees is from three-fourths of 
an inch to lj inches. While no tests have been made by the Forest 
Service, it is understood that the sapwood of cypress is easily impreg- 
nated. The treatment should extend high enough to prevent rank 
grass or bushes from coming in immediate contact with untreated 
wood, as decay, if it once gets a foothold in the sapwood, seems to 
have a tendency to extend upward on the pole. Cases have been 
called to the attention of the Forest Service where the sapwood of 
cypress poles deteriorated through the work of insects while the poles 
were piled awaiting shipment. If the bark is completely removed 
and the piles are open on skids over dry ground or raised out of reach 
of the water in swamps, this trouble may usually be avoided. 

DESIGN AND OPERATION OF POLE-TREATING PLANTS. 

EXPERIMENTAL PLANTS. 

In the first experiments the tank was shallow with a sloping bottom, 
and the poles were placed in it at such an angle that the butts were 
submerged to a height of 7 or 8 feet. (See PI. I, fig. 2.) The tank 
was substantially built of iron and was sunk nearly level with the sur- 
face of the ground, a fire box being first excavated underneath. No 
derrick is required for handling the poles when a tank of this character 
is used. A team is employed for skidding the poles alongside the 
tank, from where they may be rolled into- position across the tank and 
the butt submerged by supporting the top at the required height. 
While this type of plant makes a cheap outfit for treating a small 
number of poles, it has many defects, among which are the large 
amount of oil required to fill the tank in proportion to its treating 
capacity and the large surface of oil exposed to evaporation. 

The tank used in the experimental treatment of cedar poles at Wil- 
mington, Cal., is shown in figure 3. This is an upright cylindrical 
tank 7 feet in diameter and 8 feet deep, constructed of one-fourth- 
inch iron. 

A framework around the tank is used to support the poles in an 
upright position, and a false bottom, studded with short blunt spikes, 
prevents them from slipping. A derrick or ginpole operated by a 
power hoist is used for lifting them into and out of the tank. At the 
plant shown in the illustration an electric hoist furnished the power. 
The heating was at first done with a petroleum burner underneath the 
tank, but later a steam boiler was installed, and steam coils placed in 



RESULTS OF TREATMENTS. 



31 



the tank. Twenty 40-foot 
poles could be placed in 
the tank at one time, 
but, as most of the treat- 
ments were made by heat- 
ing and cooling in the 
same tank without change 
of oil, the capacity was 
limited to one run a day. 
This type of plant may 
be used for treating poles 
commercially where but 
comparatively few poles 
are to be treated. A stor- 
age tank with sufficient 
capacity to store at least 
one carload shipment of 
creosote should be added, 
and the capacity of the 
plant may be increased 
by the addition of a 
steam pump for changing 
the oil at the end of the 
hot bath, thus reducing 
the time required for the 
treatment. The entire 
cost of the plant with the 
improvements suggested 
would be about $1,000 or 
$1,200. A plant of this 
type, but of somewhat 
larger capacity, was sub- 
sequently built by the 
Forest Service at Norrie, 
Colo. 

COMMERCIAL PLANT FOR 
BUTT TREATMENTS. 

A general plan of a pro- 
posed plant for the butt 
treatment of poles on a 
large scale is shown in 
figure 4. This plant com- 
bines the best features 




Fig. 3. — Open tank and ginpole used in experimental pole 
treatments. 



32 PRESERVATIVE TREATMENT OF POLES. 

of the experimental plants with additional labor-saving appliances 
necessary for the economical operation of a commercial plant. This 
plant is equipped with two treating tanks, each 7 by 9 feet and 9£ 
feet deep, and with an estimated capacity of thirty 8-inch 40-foot 
western yellow pine or red cedar poles. The daily capacity, fig- 
ured on a basis of two charges for each tank, is 120 poles. Two 
storage and measuring tanks are provided, holding about 12,000 
gallons of oil each. These tanks are designed with a relatively small 
diameter in proportion to their height, so as to allow more accurate 
gauging of the amount of oil used in the treatments. The plant is 
designed to be operated by changing the oil at the end of the hot 
bath, and in order that the change may be made quickly a receiving 
tank is provided. Hot oil from the treating tank is run into the 
receiving tank and the treating tank is then refilled from the cooler 
oil in the storage tanks. From the receiving tank the oil is returned 
to the storage tanks by means of a steam pump. The connections 
may be so made that one storage tank may be used exclusively for 
hot oil and the other for cold. Also, the oil may be transferred 
directly from one treating tank to the other. Such an arrangement 
will save fuel and will reduce the time required for treatment. A few 
coils of steam pipe should be placed in the storage and receiving 
tanks for keeping the oil in liquid condition, while in the treating 
tanks sufficient steam coil is required to heat the oil rapidly during 
the treatments. A boiler of about 50 horsepower capacity will be 
required for heating and power purposes. A plant of this type is 
suitable for erection at a central yard, where from 5,000 to 30,000 or 
more poles are handled yearly. The cost of the plant, erected, will 
vary between $4,000 and $5,000, depending on the locality. 

Cost of Operation. — Following is a detailed statement of the 
estimated cost of pole treatment, based on a daily capacity of 120 
poles and a total yearly output of 30,000 poles: 

LABOR PER DAY. 

1 yard foreman $4. 00 

1 plant engineer 4. 00 

1 stationary engineer 4. 00 

2 firemen, at $2.50 5. 00 

5 laborers, at $2 10. 00 

Total : --- 27.00 

Labor charge per pole $0. 225 

FUEL PER DAY. 

2 tons coal, at $4 $8. 00 

Fuel charge per pole ■ 067 




72742°— Bull. 84—11. (To face page 32.) 



Fig. i— Plan of a commercial plant for the butt treatment of 



U. S. DEPT. OF AGRICULTURE 
FOREST SERVICE 

GENERAL ARRANGEMENT OF LOW PRESSURE TREATING PLANT 

PREPARED FOR PUBLICATION 




72742°— Bull. 84—11. (To face page 32/ 



Fig. 5.— Plan of a commercial plant where the entire pole is to be treated. 



RESULTS OF TREATMENTS. 33 

MAINTENANCE PER YEAR. 

Depreciation and repairs $500. 00 

Interest on investment in plant and preservatives 400. 00 

Total 900. 00 

Maintenance charge for pole $0. 030 

Seasoning charge per pole (interest on investment) 100 

Total treating charge, exclusive of preservative ° . 422 

The total cost of treatment, exclusive of preservative, based on a 
liberal estimate for all charges, is thus seen to be $0,422 per pole. 
In the discussions of cost of treatments this charge is called $0.45. 

DESIGN OF PLANT FOR TREATMENT OF THE ENTIRE POLE. 

The principles of the nonpressure process are the same whether 
the entire pole or only the butt is treated, only the design of the plant 
being changed When the entire pole is to be treated, in place of the 
open upright tanks, a horizontal cylinder is used, into which trucks 
bearing the timber are admitted through doors opening on the ends, 
the doors being hermetically closed after the timber is admitted. This 
cylinder is similar in appearance to those used at pressure plants, but 
is constructed of lighter metal. The storage tank, receiving tank, 
and pump are arranged in a manner similar to those in the butt- 
treating plant. 

It is recommended, however, that where a plant is erected for the 
treatment of the entire pole, it be of the low-pressure type in pref- 
erence to the nonpressure. A treating cylinder capable of withstand- 
ing a maximum pressure of 70 pounds to the square inch may be 
constructed at a cost little in excess of a nonpressure cylinder, and 
the other apparatus is essentially the same, with the addition of a 
pressure pump. In operating the low-pressure plant, the preliminary 
hot bath is given as for a nonpressure treatment; at the completion 
of the hot bath, the retort may be refilled with cooler preservatives 
and pressure applied until the desired absorption has been obtained. 

The general design of a low-pressure plant is shown in figure 5. 
The treating cylinder in this plant is 50 feet long and is capable of 
holding about eighty-five 25-foot poles. Two runs per day of ten 
hours were made, giving a daily capacity of 170 poles, which may be 
further increased by operating the plant twenty-four-hour days. The 
treating charge at a plant of this type, exclusive of preservative, will 
average about 2 cents per cubic foot of timber. A plant similar to 
the one shown in the figure costs about $10,000. 

a In this estimate no charge is included for unloading and loading poles from and to 
railway cars, it being assumed that the plant is operated in connection with a storage 
or distributing yard. 



34 



PRESERVATIVE TREATMENT OP POLES. 



COST OF POLE TREATMENTS. 

The cost of the treating operations having been set forth, and the 
amount of preservative applied having been given, it remains now 
only to compute the cost of the preservatives and to add to this the 
cost of application in order to get the total cost. 

Tank Treatment with Creosote. — -The cost of creosote in car- 
load lots (including transportation) may be placed at 10 cents per 
gallon for points east of the Mississippi River and in the vicinity of 
the Gulf ports west of the Mississippi. West of the Rocky Mountains 
the cost may be placed at 20 cents per gallon. The cost of applying 
the treatment will vary greatly in different regions, owing to the dif- 
erence in wage scales, but for convenience the general average already 
estimated will be used in all cases. 



Table 19. — Examples of cost per pole of open-tank treatments with creosote (estimated). 

BUTT TREATMENT ONLY. 



Species. 


Size of pole. 


Amount of creo- 
sote applied. 


Cost of treatment. 


Diameter. 


Length. 


Per cubic 
foot. 


Per pole. 


Preser- 
vative, a 


Opera- 
tions. 


Total. 




Inches. 
7 
7 
8 
8 
8 
7 


Feet. 
30 

30 
40 
40 
40 
35 


Pounds. 


Pounds. 
25 
50 

37.5 
62.5 
39 
35 


Dollars. 
0.30 
.60 
.90 
1.45 
.90 
.80 


Dollar. 
0.45 
.45 
.45 
.45 
.45 
.45 


Dollars. 
0.75 






1.05 


Western yellow pine 

Do 


6 
10 
6 


1.35 
1.90 
1.35 




1.25 









ENTIRE POLE TREATMENT. 



Loblolly pine. 
Do 



5 


25 


10 


80 


.95 


.15 


6 


35 


10 


180 


2.10 


.35 



1.10 

2.45 



a A gallon of creosote is estimated to be 8J pounds. 

The sizes of poles mentioned in this estimate are those mostly used 
in the experimental treatments. On account of the greater taper of 
chestnut and northern white cedar the 30-foot poles of these species 
take up about the same lateral space in the treating tank as 40-foot 
poles of the western cedar and yellow pine. Lodgepole pine tapers 
but little, and while greater tank capacity would be secured in the 
treatment of 35-foot poles of this species than for the other species 
and sizes named, the gain in this respect is more than offset by the 
high wage rate prevailing throughout the Rocky Mountain region. 

Tank Treatment with Zinc Chlorid. — The use of zinc chlorid as 
a preservative has been discussed in connection with the treatment 
of western red cedar and yellow pine poles. Supposing that the 
customary half pound of salt to the cubic foot of timber is applied 
and that the cost of operations is the same as for creosote treatment, 



INCREASED LIFE AFFORDED. 35 

the cost for the butt treatment of 40-foot poles of either of these 
species would be approximately 65 cents. 

Tank Treatment with Crude Petroleum. — Crude petroleum 
was used in the treatment of western yellow pine poles. With an 
application of 9 pounds of oil to the cubic foot (about 8 gallons per 
pole) and estimating the cost of the treating operations as before, 
the total cost of a butt treatment with this preservative is about 85 
cents. 

Brush Treatment. — The labor cost of applying a brush treatment 
is about 5 cents for each coat if the poles are treated on the skidways. 
From one-half to 1 gallon of creosote per pole will be required, de- 
pending on the timber and the thoroughness of the treatment. The 
total cost of a brush treatment with creosote, applying two coats, is 
therefore from 15 to 20 cents in the East and from 20 to 30 cents 
in the West. However, if the creosote be purchased in small quan- 
tities, as will usually be the case for brush treatments, the price will 
be higher than that used in these estimates. 

INCREASED LIFE AFFORDED BY PRESERVATIVE TREATMENT. 

Before deciding on the use of a preservative treatment, the pole user 
naturally wishes to know what length of life may be expected from 
the treated timber. In any discussion of this question it is well to 
keep clearly in mind what character of treatment is meant. Brush 
coatings of preservatives usually amply repay their cost if an increase 
of one to two years is added to the natural life of the untreated 
timber, but a great degree of permanency in the protection afforded 
should not be expected from application of so small a quantity of 
preservative. However, results already obtained in these tests indi- 
cate that an averaged increased life of at least three years may be 
expected from brush applications of good wood preservatives. 

If, instead of a light surface application, the butt of a pole be more 
deeply impregnated with the preservative, the pole will probably 
be limited by the life of the top rather than by the life of the butt. 
There are practically no data on the ultimate life of the upper portion 
of the pole, since replacements are commonly made because of failure 
of the butt. The fact that almost all pole failures are due to butt 
decay is a convincing argument for the efficiency of this form of treat- 
ment. A life of twenty years for butt-treated chestnut and western 
cedar and of twenty-two years for northern white cedar poles is 
believed to be a conservative estimate, and in the drier western 
climate it is believed that butt-treated pine poles may be depended 
on to give twenty years' service. 

While the information relative to the life of poles which have been 
treated entire is more extensive than with regard to those which 
have received butt treatment, this also is meager. The develop- 



36 



PRESERVATIVE TREATMENT OF POLES. 



ment of the ereosoting industry in this country is quite recent ; how- 
ever, authentic instances are on record of creosoted pine poles which 
have been in service twenty years and longer and are still apparently 
as good as when first set. Records of the German Postal and Tele- 
graph Department a covering fifty-two years show an average life of 
20.6 years for creosoted pine poles. 

FINANCIAL SAVING. 

Closely related to the increased life afforded by preservative treat- 
ment is the matter of the saving in money. The treatment adds to 
the cost of the pole, but also increases the length of its service. The 
question reduced to its simplest form is, Does the increased life repay 
the cost of treatment? The comparison may best be made on the 
basis of annual cost; that is, the initial cost of the pole divided by 
the number of years' service it is expected to render, allowing a reason- 
able rate of interest in the computation. The computations in Table 
20 are made on a basis of 5 per cent interest. 

Table 20. — Estimated financial saving due to creosote treatment of poles. 





Size of pole. 


Character of treat- 
ment. 


ft03 a 

+3^ ft 

PI <S-r} 
gfc| 
g£ft 


s a 

cd+3 
pi '-< 

.5 ^ 
to "8 


O — 

o 

CD o 
PI o 
"Soft 


•a 

^ CD 
+3 ^ 

e3~ 

3 ° 

•2 s 

at PI 


o 

o 

"3 
pi 
pi 
pi 
■< 




Species. 


u 

CD 
CD 

5 


a 

3 


O 

lis 




In. 

7 

7 

7 

8 

8 
7 
6 


Feet. 
30 

30 

30 

40 

40 
35 
35 




Lbs. 


Dolls. 


Dolls. 
6.00 
6.20 
6.75 

5.00 
5.20 
5.95 

7.00 
7.20 
8.05 

9.50 

9.80 
10.85 

8.00 
8.30 
9.90 

7.00 
8.25 

2.50 
4.95 


Yrs. 

10 
13 
16 

10 
13 

18 

14 
17 
22 

10 
13 
20 

3 

5 
20 

g 

20 

3 

20 


Dolls. 

0.77 

.66 

.62 

.65 
.55 
.51 

.71 

. .64 
.61 

1.23 
1.04 

.87 

2.94 
1.92 

.79 

1.62 
.66 

.92 
.40 


Dolls. 




■J Brush treatment 

(Open-tank treatment. . 


7 
25 


0.20 
.75 


0.11 




.15 


Southern white cedar 


< Brush treatment 

[Open-tank treatment. . 


5 
40 


.20 
.95 


.10 
.14 


Northern white cedar 


] Brush treatment 

[Open-tank treatment. . 


5 
50 


.20 
1.05 


.07 
.10 




1 Brush treatment '. 

1 Open-tank treatment. . 


8 
40 


.30 
1.35 


.19 




.36 


Western yellow pine 


•j Brush treatment 

[Open-tank treatment.. 


6 
60 


.30 
1.90 


1.02 
2.15 




\Open-tank treatment. . 


40 


1.25 






.96 




< Entire pole, open tank 
( or pressure. 


200 


2.45 


.52 







The financial saving is seen to be greater when treatment is applied 
to poles having little natural durability than when applied to long- 
lived timbers. This is due to two main reasons: (1) The annual 
cost of nondurable poles used untreated is relatively very high because 

"Archiv fur Post und Telegraphie, Nr. 16, Berlin, August, 1905. 



FINANCIAL SAVING. 37 

of the frequent replacements required, and (2) the cost of the treat- 
ment is relatively less (when interest on the investment is included), 
since a shorter time must elapse before the benefits begin to be realized. 
It is also obvious that, where the initial cost of the timber and of the 
setting are high, prolonging the life of poles results in greater financial 
benefit than when these costs are more moderate. 

In Table 20 the annual cost of treated and untreated poles is com- 
pared, assuming as a basis of the computations representative values 
in typical localities for each species. For example, the cost of a 
western red cedar pole is taken at southern California coast cities, 
of lodgepole pine in the Rocky Mountain region, and of loblolly pine 
in the South. Sometimes it is of greater interest to compare the cost 
of different species in the same locality, and especially to compare an 
untreated pole of a durable species with a treated pole of an ' 'inferior" 
species. 

A 7-inch 35-foot lodgepole pine pole is worth $3 f. o. b. cars in the 
mountain region of Colorado. Recently an Idaho cedar pole of the 
same size could be obtained in the same region for $5.25, including 
transportation. A butt treatment for the pine pole will cost $1.25, 
making the total cost of the treated pole $4.25. Let it be assumed, 
however, that owing to local freights the first cost of the untreated 
cedar and the treated pine at the point of use will be the same, namely, 
$5.25. Setting, which is very costly in a mountainous region, may 
be figured at $4, making the cost of either pole in place $9.25. Assum- 
ing that the untreated cedar will last in this region fifteen years, and 
the treated pine twenty years, the annual costs of the two poles 
become $0.89 and $0.74, respectively, or an annual saving of $0.15 in 
favor of the pine pole. At the rate of forty poles to the mile this 
will amount to a saving of $6 each year for each mile of line in 
operation. 

In the vicinity of Fresno, Cal., a 40-foot cedar pole brought from 
Washington costs $8, while a native pine pole may be obtained for $5. 
A heavy butt treatment of creosote may be given the latter for $1.90, 
making the total cost $6.90. Allowing $3 for setting in either case, 
the respective costs of the poles in line are $11 and $9.90. Pole users 
in this locality estimate the life of cedar at ten years, while it is be- 
lieved that the treated pine will last twenty years. On this basis the 
respective annual costs of the two poles are $1.42 and $0.79, an 
annual saving of $0.63 on every native treated pole in use. In this 
case there is a saving even in the first cost, and a relatively greater 
saving when the lives of the two poles are compared. 



38 PRESERVATIVE TREATMENT OF POLES. 

RELATION OF PRESERVATIVE TREATMENTS TO POLE SPECIFI- 
CATIONS. 

It is the practice in pole specifications to require poles of larger 
diameter than the actual service requires, in order that a certain 
amount of deterioration by decay shall be allowable before replace- 
ment is needed. For example, if it is computed that a circumference 
of not less than 28 inches of sound wood in the pole at the ground line 
is required to support the strain to which the line is liable to be sub- 
jected, and the poles used have a circumference of 36 inches at the 
ground line, then 8 inches deterioration, or the equivalent of a depth 
of decay of approximately 1J inches, is allowable before replacement 
is required. 

In some species otherwise durable the sapwood decays very 
quickly. Untreated white cedar poles in Georgia, inspected after 
being set in line four years, showed from 45 to 50 per cent of the 
number with sapwood completely decayed at the ground line, which 
amounted to an average deterioration of 4 inches in the circumfer- 
ence, equivalent to an average depth of decay of fully five-eighths of 
an inch. Cypress poles in Florida, inspected after being in the ground 
seven years, showed an average depth of decay of 0.8 inch at the 
ground line. The heartwood of these poles is sound, and in nearly 
all cases is of sufficient dimension to meet the requirements of the line 
in which they are used, although, graded by the butt circumference, 
they fall decidedly lower than their original class. If there had been 
used originally poles of the grade represented by these after the sap- 
wood has decayed, and if the butts had been well treated with creo- 
sote, so that their full size and strength would be maintained, not only 
would the poles be equally strong with those now in use, but their 
ultimate length of life would be greater, and the difference in cost 
between the two grades of poles would in some cases offset the cost 
of the treatment. Pole users are, therefore, paying money that 
might more profitably be spent for preservative treatment for poles 
of large diameter in order to secure longer life in that way. In short, 
the possibility of using lighter poles and giving them preservative 
treatment, so as to maintain their full size and strength, merits the 
attention of all pole users. 

GROWTH AND FORM OF POLES. 

Table 2 1 gives the average time required for poles of various species 
and sizes to grow; also the natural, taper of such poles, as shown by 
circumference measurements at the ground line of the pole when set 
(6 feet from the butt of the pole) and at the top. The table is com- 
piled in part from measurements made on poles used in the seasoning 
and treating tests and in part from other commercial tree studies of the 
Forest Service. 



SUMMARY. 

Table 21. — Form and rate of growth of 'pole timber. 



39 



Species. 



Location. 



Nominal 
sizes of poles. 



Diam- 
eter. 



Length. 



Age. 



Circum- 
ference 

at 
ground 
line of 
pole.a 



Circum- 
ference 
at top. 



Amount of 
taper on circum- 
ference. 



Ground 
line to 
top.a 



Aver- 
age each 
10 feet. 



Chestnut: 

Grown from seed . 

Grown from 

sprout 

Northern white cedar. 
Western yellow pine. . 

Lodgepole pine 

Loblolly pine 

Western red cedar 



Maryland, 
.do. 



•Northern Michigan 

Madera County, Cal . . . 

Montana 

Texas 

Western Washington. . 



Inches. 
7 



Feet. 
30 

30 
30 
40 
35 
35 
40 



Years. 
56 

51 
190 
65 
90 
30 
82 



Inches. 
37.3 

37.6 
36.4 
38.6 
30.8 
28.9 
38.9 



Inches. 
27.8 

28.4 
23.9 
25.1 
22.0 
22.0 
27.0 



Inches. 
9.5 

9.2 
12.5 
13.5 
8.8 
6.9 
11.9 



Inches. 
4.0 

3.8 
5.2 
4.0 
3.0 
2.4 
3.5 



a 6 feet from butt. 

A striking contrast appears in this table between the rate of growth 
of northern white cedar and loblolly pine. The cedar, under natural 
forest conditions, is a very slow-growing tree and will become increas- 
ingly scarce as a source of pole supply, as present stands become more 
and more exhausted. On the other hand, loblolly pine is a good 
example of a number of more rapid-growing species which, possessing 
all essential qualities for poles except durability — a defect which may 
be overcome by preservative treatment — will, through their rapidity, 
of growth and ease of reproduction, continue to be available in suffi- 
cient quantities and at moderate prices, thus assuring pole users of 
supplies for future needs. 

SUMMARY. 

The more important conclusions from the investigations discussed 
in this bulletin are: 

Seasoning of poles reduces their weight, commonly from 16 to 30 
per cent, and even more for some species, with a corresponding 
decrease in the cost of transportation. Thorough seasoning is essen- 
tial if the poles are to be treated with preservatives. 

In general, poles cut during the spring and summer lose weight 
most rapidly. Poles cut during autumn and winter lose weight less 
rapidly, but more regularly. Too rapid seasoning may be detrimental 
to the timber by causing excessive checking. 

Shrinkage of poles during seasoning is very slight, and does not 
exceed 1 per cent on the circumference. 

A simple and inexpensive way of using a preservative consists in 
applying it to the surface of the pole with a brush. Butt treatments 
made in this manner with a good preservative may be expected to 
add two to three years to the life of the poles and more than repay 
their cost, but are not as effective as impregnating the wood with the 
preservative. 



40 PRESERVATIVE TREATMENT OF POLES. 

Impregnation of many pole timbers, especially the sapwood of 
round timbers, may be successfully accomplished in open tanks, 
without the use of artificial pressure, by immersions in hot and cold 
preservative, the cold following the hot. 

The open-tank process for the treatment of poles has the advan- 
tage that it is possible to apply the preservative to the butts only, 
with a great saving in the amount used. Plants for butt treatments 
may be constructed in a simple and inexpensive manner. 

Preservative treatment is profitable financially, the increased 
durability of the timber decreasing the annual service charge. Rela- 
tively greater benefits are derived from the treatment of nondurable 
woods than from the treatment of those which possess great natural 
durability. 

Preservative treatment makes possible the use of poles of smaller 
butt circumference, since allowances usually made for deterioration 
by decay need not be considered, when it is certain that the full size 
and strength of the poles will be retained through a long period of 
years. 

By the application of preservative treatment, many species of 
timber not naturally durable and formerly not considered suitable 
for poles may be used for this purpose, thus opening up new sources 
of supply, and greatly relieving the pole situation from the threatened 
exhaustion of those woods now most commonly used. 



APPENDIX. 



REPORT ON INSPECTION OF EXPERIMENTAL POLES. 

In the summer of 1905 a number of treated and untreated poles 
were set in the Augusta-Savannah and Helena-Meldrin a lines of the 
Southern Bell Telephone and Telegraph Company, near Savannah, 
Ga. The experiment dealt with 816 poles, one half southern white 
cedar and the other half chestnut, the treated poles being alternated 
with the untreated ones, and the series arranged as shown in the 
following plan: 6 

Table 22. — Setting plan of poles in experimental line established in cooperation with the 
Southern Bell Telephone and Telegraph Company near Savannah, Ga. 



Pole 
No. 


Preservative a sold as — 


Condition. 


Pole 

No. 


Preservative a sold as — 


Condition. 


1 


Avenarius Carbolineum 


Seasoned. 

Do. 

Do. 
Green. 
Seasoned. 

Do. 

Do. 
Green . 
Seasoned. 

Do. 

Do. 
Green. 
Seasoned. 

Do. 

Do. 
Green. 
Seasoned. 


18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 




Seasoned. 


2 




Do. 


3 


Avenarius Carbolineum 


No treatment 




4 


Imperial Wood Preservative 




5 


S. P. F. Carbolineum 


Do. 


6 




Imperial Wood Preservative 


Do. 


7 


S. P. F. Carbolineum 


Do. 


8 




Do. 


9 






Do. 


10 






Do. 


11 








1? 




Tar 




13 






Do. 


14 


No treatment 


Tar 


Do: 


15 








16 


No treatment 


Tar 


Do. 


17 

















a See page 46 for analysis of preservatives. 

The series is repeated twelve times for each species, series No. 2 
beginning with pole No. 35, series No. 3 with pole No. 69, etc. 

The inspection of the line was made in April and May, 1909, by 
representatives of the American Telegraph and Telephone Company 
and of the Forest Service. A careful examination was made of each 
pole and its condition noted. In Tables 23 and 24 and in figure 6 
the relative efficiencies of the various treatments are compared by 
grouping the poles with reference to the amount of decay in the 
sapwood at or near the ground line. The number and percentage 
of poles having decay in the heartwood is also shown in the tables. 

a In Forest Service Circular No. 104 the line is referred to as the "Savannah- 
Abbeville-Eastman " line. 

b See "Southern white cedar," page 20, and "chestnut," page 18, for record of 
treatments. 

41 



42 



PRESERVATIVE TREATMENT OF POLES. 





SOUTHERN WH 


ITE CEDAR 

TAP COAT/NO (GPEEN POLES) 
ONTPEATED (SEASONED POLES) 
TAP OOAT/NS (SEASONED POLES) 
l/A/TPEATEL/ (GPEEN POLES) 

PRESERVATII/E SOLD AS 

CPEOL/A/ 2 COATS 

PRESERVA T/VE SOLD AS 

S.P.P. CAPBOL/NEUM(/ COAT) 

PRESERVATIVE SOLD AS 

/MPEPJAl WOOD PPESEPVAT/vE^ 2 COATS 

PRESERVATIVE SOLO AS 

S.PE CAflBOL/NEUM (2 COATS) 

PRESERVATIVE SOLD AS 

AfENAP/VS CAPBOL/NEDM, 2 COATS 

PRESERVA Tl VE SOLD AS 

SP/P/TT/NE, S COATS 
CPEOSOTE, .3 CO/ITS 
CPEOSOTE, 2 COATS 
























fe:tf:'« 








































ssaws 










■:::| 






























EsJ^ 










•.•■.•!•;•! 


































US*; 


»5%SS? 


i^i^ 


f^&4 


^^ 


^■•>: 










































































































































































t 


7 /O 20 SO 40 SO 60 70 <SO JO /6 

pepcene or poles 

CHEST 


O 

NUT 




■XA 




















DNTPEATE//(SPEEN POLES) 
l/NTPEATEO (SEASONED POLES) 
TAP COAT/NG (GPEEN POLES) 
P/NE TAP? 

TAP COAT/A/G (SEASOA/EO POLES) 
CPEOSOTE, 7 COAT 

PRESERVATIVE SOLD AS 

AVENAP/US CAPBOL/NEC/N, /COAT 

PRESERVA TIVE SOLD AS 

/MPEB/AL WOOD PPESEPMT//E, 2 COATS. 
CPEOSOTE, 2 COATS 

PRESERVATIVE SOLD AS 

SP/P/TT/NE, 3 COATS 
C/fEOSOTE, J COATS 

PRESERVATIVE SOLD AS 

CPEOL/A/, ^ COATS 

PRESERVATIVE SOLD AS 

S.P.P.CAPBOL/NEUM, 2 COATS 

PRESERVATIVE SOLD AS 

AvENAP/OS CARBOL/NENA/, 2 COATS 






















•1:W 


\ 






































■zm? 


\ 






































VW 


'■*& 






































W£& 


*%*** 


■VS//, 


^ 


































B%# 


V/Ssi- 


y;s//s 


%^ 


^^ 


;^^ 


*fe^ 
































































































































































^ 




















6 


> /O 20 30 40 SO SO TO SO SO /C 
PERCENT OE POLES 

LEGE 

■■ 'SOCIAIO 1 1 

S^Si LESS TrtA/V /O'A OP SAPWOOO |:*:-:-:*J 
OECAYED (cEOAR POLES ) 

Egg%3 PARTIAL DECAY 1 OE SAPWOOO 


TOTAL DECAY OP SAPWOO0 

HfOPE E//AAI 10 % OP" SAPWOOO 
DECAYED (CEDA/? POLES) 

(c//EsrA/t/r poles) 



Fig. 6. — Diagram showing condition of experimental poles. 



APPENDIX. 



43 



It should not be inferred, however, that because a pole is classed 
in the latter group decay is necessarily of a serious character, as in 
most cases the amount of heartwood decayed is small. The class 
indicates only that decay has extended beyond the sapwood portion 
into the heartwood without regard to the amount of decay. A very 
few of the poles were decayed to such an extent that replacement 
was required. The number of such is also noted. 

Table 23. — Summary of condition of southern white cedar poles in experimental line 
established in cooperation with the Southern Bell Telephone and Telegraph Company 
near Savannah, Ga. 



Treatment. 


Total 
num- 
ber. 


Sound 
poles. 


10 per cent 
or less of 
sapwood 
decayed. 


More than 
10 per cent; 
less than 
total decay 
of sap- 
wood. 


Total 
decay 
of sap- 
wood. 


Decay in 
heart- 
wood. 


Replace- 
ment, 
needed. 


Untreated seasoned poles . . 

Untreated green poles 

Preservative sold as Ave- 
narius Carbolineum (2 


104 
96" 

24 

21 

3 
33 
15 

24 

24 

24 
12 
24 


No. 


p.ct: 


No. 
1 

7 

7 
5 


P.ct. 
1 

7 

29 
24 


No. 
51 
45 

1 
2 
2 


P.ct 
49 
47 

4 
9 
67 


No. 

52 
43 


P.ct. 
50 
45 


No. 
6 
2 

1 


P.ct. 

6 
2 

4 


No. 
1 


P.ct. 
1 


1 

16 
14 

1 

23 
10 

16 

14 
' 5 


1 

67 
67 

33 

70 
67 

67 

5S 
21 








Preservative sold as S. P. 

F. Carbolineum (2 coats). 
Preservative sold as S. P. 

F. Carbolineum (1 coat) . . 






















10 
5 

8 

9 
13 


30 
33 

33 

38 
54 
































Preservative sold as Spirit- 


















Preservative sold as Impe- 
rial Wood Preservative 


1 

6 
10 
12 


4 

25 
83 
50 














Preservative sold as Creo- 














Coal tar (green poles) 

Coal tar (seasoned poles).. . 


2 

11 


17 
46 














1 


4 























Table 24. — Summary of condition of chestnut poles in experimental line established 
in cooperation with the Southern Bell Telephone and Telegraph Company near Savan- 
nah, Ga. 



Treatment. 



Total 
num- 
ber. 



Sound 
poles. 



Partial de- 
cay of sap- 
wood. 



Total de- 
cay of sap- 
wood. 



Decay in 
heartwood. 



Replace- 
ment, 
needed. 



Untreated seasoned poles 

Untreated green poles 

Preservative sold as Avenarius 
Carbolineum (2 coats) 

Preservative sold as Avenarius 
Carbolineum (1 coat) 

Preservative sold as S. P. F. Car- 
bolineum (2 coats) 

Preservative sold as S. P. F. Car- 
bolineum (1 coat) 

Creosote (1 coat) 

Creosote (2 coats) 

Creosote (3 coats) 

Preservative sold as Spirittine (3 
coats) 

Preservative sold as Imperial 
Wood Preservative (2 coats). . . 

Preservative sold as Creolin (2 
coats) 

Coal tar (green poles) 

Coal tar (seasoned poles) 

Pine tar 



114 
95 

18 

4 

18 

2 
3 
39 

6 

24 

24 

24 

8 

21 

7 



No. 



P.ct. 



50 

78 

100 
33 

62 

67 

63 

63 

71 
..... 



No. 
12 

7 

1 
1 
3 



P.ct. 
11 
7 

6 

25 

17 



No. 
102 



P.ct. 
89 
93 



25 

6 



No. 
70 
35 



P.ct. 
61 
37 



No. 
1 



P.ct. 
1 
2 



44 PRESERVATIVE TREATMENT OE POLES. 



DISCUSSION OF RESULTS. 

SOUTHERN WHITE CEDAR POLES. 



With the exception of the tar and creolin treatments and a few 
treatments with only one coat of carbolineum or creosote, from 58 
to 70 per cent of the treated cedar poles are in a perfect state of 
preservation. On the other hand, the sapwood of the untreated 
poles is in nearly every case completely or almost completely decayed, 
and in a few cases the decay extends to the heartwood. While all 
the poles having more than 10 per cent decay, yet less than total 
decay of the sapwood, are put into one group, the proportion of 
the untreated poles in this group that falls near the upper limits 
in amount of decay found is much greater than that of the treated 
poles. 

When decay occurred in the treated poles (referring only to those 
treatments which show a high percentage of sound poles) it was 
found most often in sapwood which was not penetrated by the pre- 
servative, the outer wood to a depth of perhaps a quarter of an inch, 
or as deep as the preservative had penetrated, being in a sound 
condition. Moreover, such decay was usually small in amount 
and occurred in strips frequently only a few inches wide, extending 
lengthwise of the pole. White ants, or termites, were very com- 
monly found in the poles; like decay, their destruction was confined 
largely to the untreated poles and to wood which the preservative 
had not reached beneath the protecting bands of the treated poles. 
These insects excavate galleries in the wood, and it is believed that 
to a considerable extent they hasten decay.® However, as the borings 
of the termites were in nearly all cases accompanied by decay, it 
was usually impossible to determine which agency was primarily 
responsible for the destruction, and in the tables no distinction is 
made between these two causes of deterioration. N 

The amount of deterioration was determined by measuring the cir- 
cumference just above the decayed portion and the circumference of 
the sound wood at the point of greatest decay, first scraping away 
the disintegrated wood. The difference between these two measure- 
ments gives the approximate amount of deterioration, which for 100 
poles, having all the sapwood decayed, was on an average 4.03 inches. 
This corresponds to an average depth of decay of approximately five- 
eighths of an inch for these poles. Other poles similarly decayed, 
but on which good measurements could not be obtained, are not 
counted in this average. 

° It is stated by the Bureau of Entomology that white ants, while usually confining 
their work to the outer layers of wood where there is incipient decay, will often com- 
pletely honeycomb the sound wood of poles. 



APPENDIX. 



45 



CHESTNUT POLES. 



The same general conditions apply to the chestnut poles, but decay 
is less in amount, although the number of poles having decay of 
heartwood is very much greater. The sapwood of chestnut is narrow 
and its decay does not appreciably affect the strength of the pole. 
Decay does not, however, halt when it reaches the heartwood, but 
continues steadily, although probably at a decreased rate. The 
average depth of decay on 222 chestnut poles having at least all of 
the sapwood decayed was found to be 0.25 of an inch. 

IRREGULARITIES IN RESULTS. 

Several irregularities appear in the results of the tests as shown by 
the tables ; these, however, may be regarded as largely accidental and 
do not destroy the value of the whole. For example, two chestnut 
poles were treated with only one coat of the preservative sold as car- 
bolineum. Both are sound, and therefore the percentage of sound 
poles under this head is 100. Eighteen poles were given two coats of 
the same preservative ; of these 14, or 78 per cent, are sound. It is 
not a necessary conclusion that one coat of this preservative is more 
efficient than two coats, although it might be concluded that one coat 
affords an effective treatment. Even the latter conclusion is not 
entirely warranted after a comparison with the results obtained from 
one and two coats of other preservatives and from one coat of the 
same preservative on cedar poles. A somewhat similar case is shown 
in the creosote treatments on cedar poles. Thirty-three were treated 
with two coats of creosote and 15 with three coats. Seventy per cent 
of those treated with two coats are sound and only 67 per cent of 
those receiving three coats. The conclusion is not that two coats 
are more efficient than three, but in the absence of other data we may 
infer that a third coat does not add to the efficiency of the treatment. 



HEIGHT OF DECAY ABOVE GROUND LINE. 

The height above ground line to which decay extended was noted 
on 301 cedar poles. On most the decay did not extend upward more 
than one-half foot, and in relatively few cases did it extend more than 
2 feet above ground, the height depending to a large extent on the 
character of the vegetation in the immediate vicinity of the pole. 

Table 25. — Height of decay above ground line — Cedar poles. 



Height of decay above ground. 


Number 
of poles. 


Per 
cent. 




205 
96 
46 
18 
5 


68 
32 
15 
6 
2 













46 



PRESERVATIVE TREATMENT OF POLES. 



The sapwood of chestnut poles has a tendency to flake off, and the 
surface of the poles is frequently scaly. Aside from this scaling off 
of the sapwood, decay did not extend any appreciable distance above 
the ground. 

It appears from Table 25 that if cedar poles be treated to a height 
of 2 to 3 feet above the ground, ample protection from decay will be 
afforded. Treatment need not extend any higher on chestnut poles, 
and possibly may be somewhat lower with safety. 



DETERIORATION SHOWN BY CHANGE OF GRADES. 

A grading of the untreated cedar poles was made, based on the butt 
circumference given in the specifications of the American Telephone 
and Telegraph Company and upon the measurements, already 
described, of the poles after use. The number of poles in each class 
graded by circumference above the decayed portion and the grading 
of the same poles based on the circumference of sound wood at the 
point of greatest decay is shown in Table 26: 

Table 26. — Grading of -poles based on original butt circumference and circumference of 
sound ivood at time of inspection. 



Classes. 


Number of 
poles, 

graded by 
original 
circum- 
ference. 


Number of poles, graded by circum- 
ference of sound wood at time of 
inspection, by classes. 


A. 


B. 


c. 


D. 


E. 


Below 
E. 


A 

B 

C 

D 

Total.... 


56 
70 
35 
18 


16 


31 

27 . 


9 

32 

9 








9 
10 
5 


1 
6 
4 


1 

10 
9 












179 


16 


58 


50 


24 


11 


20 



Of the 179 poles included in the above classification, only 57 have 
not been lowered in grade because of deterioration in circumference 
due to decay. The remaining 122, or 68 per cent, have deteriorated 
enough to require that they be classed at least one grade lower, and, 
of these, 45 must be classed at least two grades lower, while of a few 
the deterioration is even greater. 

ANALYSIS OF PRESERVATIVES USED IN THE TREATMENT OF 
POLES SET IN THE AUGUSTA-SAVANNAH AND HELENA-MELDRIN 
LINES. a 

Samples of the preservatives used for the treatment of experi- 
mental poles in the Augusta-Savannah and Helena-Meldrin lines 
were analyzed by the engineering department of the American Tele- 
phone and Telegraph Company. These analyses were made in 

a Reprinted from Forest Service Circular 104, with names of preservatives added. 



APPENDIX. 



47 



accordance with the company's methods for the analysis of creosote 
and carbolineum standard at the time these treatments were made 
(1905). The results of the analyses follow: 

Preservative sold as Avenarius Carbolineum. a 



Color 

Specific gravity at 17° C. . . 

Mineral matter 

Flashing point 

Burning point 

Distillates: 

Below 235° C 

Loss 

From 235° C. to 315° C 
Residue above 315° C. 
Solids, 1.7° C to 4.4° C 
Tar acids 



Red-brown... 

1.121 

0.160 

137° C 

164° C 

0.41 per cent. . 
0.19 per cent.. 
19.16 per cent. 
70.24 per cent. 
No separation 
1.12 per cent.. 



Red-brown. 
1.122. 
0.050. 
137° C. 
168° C. 

0.61 per cent. 
0.22 per cent. 
26.97 per cent. 
72.20 per cent. 
No separation. 
1.16 per cent. 



a Manufacturers' analysis: Color, red-brown; specific gravity at 21° C, 1.126; viscosity at 21° 0, 115.860; 
mineral matter (ash), 0.047 per cent; flashing point, 127° C; burning point, 179° O; distillates — from 
220° C. to 260° C, 4.5 per cent; rom 260° C. to 274° C, 1 per cent; from 274° C. to 302° C, 20 per cent; naphtha- 
lene, very slight trace; mineral acids (HCl,H.2SO.i), very slight trace; phenols, very slight trace. 

Preservative sold as S. P. F. Carbolineum. 



Series I. 



Series II. 



Color 

Specific gravity at 17° C. . . 

Flashing point 

Burning point 

Distillates: 

Below 235° C 

Loss 

From 235° C. to 315° C 

Residue over 315° C... 
Solids, 1.7° C. to 4.4° C... 

Tar acids 

Mineral matter 



Red-brown... 

1.134 

135° C 

163° C 

0.35 percent.. 
0.13 per cent.. 
28.84 per cent. 
70.68 per cent. 
No separation 
1.30 percent.. 
0.31 percent.. 



Red-brown. 
1.134. 
135° C. 
162° C. 

0.31 per cent. 
0.19 per cent. 
30.10 per cent. 
69.40 per cent. 
No separation. 
1.30 per cent. 
0.47 per cent. 



Preservative sold as Spirittine. a 



Series I. 



Series II. 



Color 

Specific gravity at 17° C... 

Flashing point 

Burning point 

Distillates: 

Below 235° C 

Loss 

From 235° C. to 315° C 

Residue above 315° C. 
Solids, 1.7° C. to 4.4° C... 

Tar acids 

Mineral matter 



Green-black. . 

1.032 

90°C 

99° C 

15.14 per cent. 
0.65 per cent.. 
26.23 per cent. 
57.98 per cent. 
No separation 
15.40 per cent 
0.14 per cent.. 



Green-black. 
1.031. 
90° C. 
101° C. 

14.97 per cent. 
0.53 per cent. 
25.60 per cent. 
58.90 per cent. 
No separation. 
16.30 per cent. 
0.02 per cent. 



a Manufacturers' analysis: Color, green-black; specific gravity, 1.03; flashing point, 78° C; burning 
point, 93° C; distillates— below 315° C, 37.40 per cent; above 315° C, 52.69 per cent; coke and gas corre- 
sponding to, 9.91 per cent. 



48 



PRESERVATIVE TREATMENT OE POLES. 
Coal-tar creosote. 



Series I. 



Series II. 



Color 

Specific gravity at 38° C... 

Distillates: 

Below 170° C 

From 170° C. to 205° C 
From 205° C. to 210° C 
From 210° C. to 235° C 
From 235° C. to 240° C 
From 240° C. to 270° C 
From 270° C. to 300° C 
'Residue above 300° C. 
Loss 

Total 

Naphthalene 

Liquid at 

Tar acids 



Greenish-brown 
1.035 



0.17 per cent. 

1.25 percent. 

1.14 per cent. 
43. 96 per cent . 

6. 66 per cent. 
19. 48 per cent. 
10. 07 per cent. 
17. 00 per cent. 

0.27 per cent. 



100. 00 per cent. 
45.10 per cent.. 

38° C 

9 c. c 



Greenish-brown. 
1.035. 

0. 09 per cent. 

0. 70 per cent. 

0. 74 per cent. 
45. 92 per cent. 

6. 12 per cent. 
20. 03 per cent. 

9. 61 per cent. 
16. 30 per cent. 

0. 49 per cent. 



100. 00 per cent. 
46.00 per cent. 
38° C. 
8.3 c. c. 



Preservative sold as Imperial Wood Preservative. 



Color 

Specific gravity at 17° C. . . 

Flashing point 

Burning point 

Distillates: 

Below 235° C 

Loss 

From 235° C. to 315° C 

Residue at 315° C 

Solids 1.7° C. to 4.4° C 

Tar acids 

Mineral matter 



Series I. 


Series IT. 


Greenish-black 


Greenish-black. 


1.035 


1.035. 


115° C 


111° C. 


129° C 


123° C. 


2.51 per cent 


3.65 per cent. 


0.29 per cent 


0.51 per cent. 


26.00 per cent 


24.74 per cent. 


71.20 per cent 


71.10 per cent. 


No separation 


No separation. 


13.70 per cent 


11.80 per cent. 


0.04 per cent 





Preservative sold as Creolin. 



Series I. 



Series II. 



Color 

Specific gravity at 38° C 

Distillates: * . 

Below 170° C 

From 170° C. to 205° C. 

From 205° C. to 210° C. 

From 210° C. to 235° C. 

From 235° C. to 240° C. 

From 240° C. to 270° C. 

From 270° C. to 300° C. 

Above 300° C 

Loss 



Total... 
Naphthalene. 

Water 

Tar acids 

Note 



Light brown . 
1.007 



26. 66 per cent... 

17. 39 per cent... 

9. 27 per cent . . . 

25. 92 per cent... 

> 15. 98 per cent... 

4. 24 per cent . . . 
0. 54 per cent . . . 



100. 00 per cent 

35.19percent 

20.00 per cent 

19c. c 

Sticks and other 
foreign matter 
present. 



Light brown. 
1.005. 

96. 90 per cent. 
0. 10 per cent. 



0. 15 per cent. 

0. 85 per cent. 
2. 00 per cent. 



100. 00 per cent. 

None. 

90 per cent. 

1 c. c. 

Sticks, sand, and 
other foreign 
matter present. 



APPENDIX. 



49 



DETAILED TABLES AND CURVES SHOWING RATE OF SEASONING 

OF POLES.- 

Table 27. — Rate of seasoning of southern white cedar poles at Wilmington, N. C. a 



Duration 
of sea- 
soning. 


Spring cut. 


Summer cut. 


Autumn cut. 


Winter cut. 


Weight 

per cubic 

foot. 


Moisture 
content, b 


Weight 

per cubic 

loot. 


Moisture 
content, s 


Weight 

per cubic 

foot. 


Moisture 
content, b 


Weight 

per cubic 

foot. 


Moisture 
content. 6 


Months. 

1 
2 
3 
4 
5 
6 
7 
8 
9 

10 
11 
12 
13 
14 
15 
16 
17 


Pounds. 
34.8 
27.7 
26.3 
25.9 
25.7 
25.6 
25.5 
25.4 
25.4 
25.3 
25.0 


Per cent 
of dry- 
weight. 
68 
34 
27 
25 
24 
24 
23 
23 
23 
22 
21 


Pounds. 
36.6 
28.5 
.26.8 
26.5 
26.5 
26.7 
26.8 
27.0 
26.9 
26.7 
26.7 
2G.6 
26.5 
26.4 
26.2 
26.2 
26.1 
26.0 


Per cent 
of dry 

weight. 
77 
38 
29 
28 
28 
29 
29 
30 
30 
29 
29 
29 
28 
28 
27 
27 
26 
26 


Pounds. 
38.7 
29.5 
27.9 
27.7 
27.5 
27.2 
26.7 
26.5 
26.2 
26.0 
25.9 
25.7 
25.7 
25.7 
25.7 
25.7 
25.8 


Per cent 
of dry 

weight. 
87 
43 
35 
34 
33 
31 
29 
28 
27 
26 
25 
24 
24 
24 
24 
24 
25 


Pounds. 

38.9 
29.9 
28.3 
26.7 
26.5 
26.0 
25.7 
25.6 
25.6 
25.6 
25.5 
25.5 
25.5 
25.5 


Per cent 
of dry 

weight. 
88 
44 
37 
29 
28 
26 
24 
24 
24 
24 
23 
23 
23 
23 












































i 





a Based on six hundred 25-foot and 30-foot poles. The average volume of 30-foot poles was 20.76 cubic 
feet, and of 25-foot poles, 14.53 feet. 
b Dry weight, according to Sharpless (Vol. IX, Tenth Census), is 20.7 pounds per cubic foot. 





1 
















































k 




























in 








































r 


















1 






















V* 








^-, 










\^ 
































































































, 




\ 

















13 /■*• /S /B 17 



Fig. 7. — Rate of seasoning of southern white cedar poles, Wilmington, N. C. 



50 PRESEKVATIVE TREATMENT OP POLES. 

Table 2S. — Rate of seasoning of chestnut poles at Pisgah, N. C. a 



Duration 
of sea- 
soning. 


Spring cut. 


Summer cut. 


Autumn cut. 


Winter cut. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Months. 



1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 


Pounds. 
55.2 
52.3 
50.2 
49.1 
48.4 
48.1 
47.7 
46.8 


Per cent 
of dry 

weight. 
97 
86 
79 
75 
72 
71 
70 
67 


Pounds. 
53.5 
50.6 
48.3 
47.0 
46.3 
46.0 
45.8 
45.7 
45.7 
45.3 
44.8 
43.8 
43.5 
43.3 
43.3 
43.2 


Per cent 
of dry 

weight. 
91 
80 
72 
67 
65 
64 
63 
63 
63 
61 
60 
56 
55 
54 
54. 
54 


Pounds. 
54.7 
51.7 
50.3 
49.9 
49.6 
49.0 
48.8 
48.3 
47.3 
46.4 
45.8 
45.5 
44.8 


Per cent 
of dry 

weight. 
95 
84 
79 
78 
77 
75 
74 
72 
69 
65 
63 
62 
60 


Pounds. 
56.5 
54.3 
52.7 
51.5 
50.7 
49.8 
49.2 
48.3 
47.7 
47.5 
47.2 


Per cent 
of dry 
weight. 
101 
93 
88 
83 
81 
77 
75 
72 
70 
69 
68 



































































a Based on six hundred 25-foot and 30-foot poles. The average volume of 30-foot poles was 21.12 cubic 
feet, and of 25-foot poles 14.70 cubic feet. 

Table 29. — Rate of seasoning of chestnut poles at Dover, N. J. a 



Duration 
of sea- 
soning. 


Spring cut. 


Summer cut. 


Autumn cut. 


Winter cut. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Months. 

1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 


Pounds. 
50.8 
49.0 
47.5 
46.5 
46.0 
45.5 
45.1 
44.5 


Per cent 
of dry 

weight. 
81 
75 
69 
66 
64 
62 
61 
59 


Pounds. 
51.5 
48.8 
47.4 
46.8 
46.6 
46.4 
46.2 
46.1 
45.7 
45.0 
44.0 
43.4 
43.0 
42.7 
42.4 


Per cent 
of dry 
weight. 
83 
74 
69 
67 
66 
65 
65 
64 
63 
. 60 
57 
55 
53 
52 
51 


Pounds. 
50.8 
48.4 
47.2 
47.0 
46.8 
46.6 
46.2 
45.5 
44.7 
43.9 
43.2 
42.8 
42.5 
42.2 


Per cent 
of dry 

weight. 
81 
72 
68 
67 
67 
66 
65 
62 
59 
56 
54 
52 
51 
50 


Pounds. 
51.8 
50.8 
49.8 
48.7 
47.5 
46.3 
45.3 
44.5 
44.1 
43.8 
43.2 


Per cent 
of dry 

weight. 
85 
81 
77 
73 
69 
65 
61 
59 
57 
56 
54 



















































a Based on four hundred 30-foot poles. Volume, 22 cubic feet. 



APPENDIX. 51 

Table 30. — Rate of seasoning of chestnut poles at Thorndale, Pa. a 



Duration 
of sea- 
soning. 


Spring cut (vol- 
ume, 20 cubic feet). 


Summer cut (vol- 
ume, 21 cubic feet). 


Autumn cut (vol- 
ume, 20 cubic feet). 


Winter cut (vol- 
ume, 20 cubic feet) 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Months. 



1 

2 

3 

4 

5 

6 

7 

8 

9 
10 
11 
12 
13 
14 
15 
17 
19 
20 
21 
23£ 


Pounds. 
53.0 
50.1 
47.9 
46.4 
45.4 
44.8 
44.4 
43.9 
43.6 
43.6 
43.6 
42.4 
43.0 
42.5 
42.3 
42.1 
41.8 
41.5 
41.3 
41.0 
40.7 


Per cent 
of dry 

weight. 
89 
78 
71 
65 
62 
60 
58 
56 
55 
55 
55 
51 
53 
51 
51 
50 
49 
48 
47 
46 
45 


Pounds. 
54.0 
50.1 
48.2 
47.4 
47.1 
46.8 
46.7 
46.4 
46.1 
45.7 
45.2 
44.7 
44.2 
43.7 
43.3 
42.9 
42.5 
42.3 
42.1 
41.7 
41.3 


Per cent. 
92 
78 
72 
69 
68 
67 
66 
65 
64 
63 
61 
59 
57 
56 
54 
53 
51 
51 
50 
49 
47 


Pounds. 
52.7 
50.5 
49.3 
48.8 
48.6 
47.9 
46.9 
45.7 
44.8 
44.1 
43.8 
43.2 
42.5 
41.8 
41.6 
41.7 
41.9 
41.8 
42.2 


Per cent. 
88 
80 
76 
74 
73 
71 
67 
63 
60 
57 
56 
54 
51 
49 
48 
49 
49 
49 
50 


Pounds. 
52.9 
51.7 
50.4 
49.1 
47.6 
46.3 
45.1 
44.3 
43.6 
42.9 
42.4 
42.0 
41.8 
41.6 
41.5 
41.5 
41.5 


Per cent. 
88 
84 
80 
75 
70 
65 
61 
58 
55 
53 
51 
50 
49 
48 
48 
48 
48 



























Table 31. 



a Based on six hundred 30-foot poles. 
-Rate of seasoning of chestnut poles at Parkton, Md. a 



Duration 
of sea- 
soning. 


Fall cut. 


Winter cut. 


Spring cut. 


Summer cut. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


AVeight 

per cubic 

foot. 


Moisture 
content. 


Months. 

1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 


Pounds. 
56.4 
52.3 
51.2 
50.7 
50.4 
49.9 
49.3 
48.4 
47.4 
46.5 
45.8 
45.3 
44.9 


Per cent 
of dry 

weight. 
85.4 
72.0 
68.4 
66.9 
65.8 
64.3 
62.2 
59.2 
56.0 
53.0 
50.8 


Pounds. 
56.4 
53.9 
52.5 
51.3 
50.1 
48.8 
47.7 
46.7 
46.0 
45.4 


Per cent. 
85.6 
77.4 
72.6 
68.7 
64.8 
60.6 
56.8 
53.7 
51.2 
49.3 


Pounds. 
55.6 
51.8 
49.9 
48.6 
47.6 
46.7 
46.1 


Per cent. 
83.0 
70.5 
64.3 
60.0 
56.5 
53.7 
51.7 


Pounds. 
56.1 
51.0 

48.8 
47.9 

47.4 


Per cent. 
84.4 
67.9 
60.6 
57.5 
55.9 


































49.1 

47.8 







































a Based on five hundred and fifty 30-foot poles. Oven dry weight, determined on disks cut from the 
poles, 30.4 pounds per cubic foot. Average volume, 20 cubic feet. 



52 



PRESERVATIVE TREATMENT OE POLES. 



58 

vl 

!« 

kl 

k 
:*; 48 

S 46 

44 




































h, 


























\^x 




V 1 - 


























^ 

























































































k 

J; 

^ B4-.2. 



5; 77.6 



k 

I sa 

% 

K 57.<? 



O / a 3 4 5 6 7 a , 9 /O // /2 /3 

OCT. A/OV. DEC. JAN. FEB. MAP. APR. MAY JUNE JULY AUG. SEPT. OCT. 
T/ME SEASON /NG~MOA/T/-tS 



44J 



Fig. 8. — Rate of seasoning of chestnut poles, Parkton, Md. 
Table 32. — Rate of seasoning of northern white cedar poles at Escanaba, Mich. « 



Duration 
of season- 
ing. 


Spring cut. 


Summer cut. 


Autumn cut. 


Winter cut. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Months. 



1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 


Pounds. 
31.9 
27.7 
26.9 
26.7 


Per cent. 
77 .4 
53.8 
49.7 
48.4 


Pounds. 
32.7 
29.1 
27.3 
26.8 


Per cent. 
81.7 
61.4 
51.9 
49.1 


Pounds. 
32.2 


Per cent. 
79.0 


Pounds. 
34.2 


Per cent. 
90.0 














33.6 
27.5 
25.6 
24.8 
24.2 


86.4 
53.0 
42.3 
37.5 
34.3 














31.9 
25.7 
24.0 
23.2 
22.9 


77.2 
43.0 
33.2 
29.0 
27.2 






















26.6 
25.3 
24.4 
23.9 
23.5 


48.0 
40.5 
35.7 
32.9 
30.7 


















26.0 
24.5 
24.1 
23.8 


44.2 
36.0 
33.7 
32.3 


































1 


1 





a Based on 450 poles. Ovendry weight=18 pounds per cubic foot. Average volume, 17.62 cubic feet. 



winter co?. 



ki 26 

















AU 


TUMfi. 


' CU7 




"v 


\ 






























> 












V 


* 






c 




























N^5 








leu 


r 










A 


























~—< 
























^ 


L 


■ — 







































.APR. MAY JUNE JUL Y AUS. SEPT. OCT. NOV. DEC. JAN. FEB. MAP. APR. MAY JUNE JULY 
TIME SEASONING -MONTHS 



Fig. 9. — Rate of seasoning of northern white cedar poles, Escanaba, Mich. 



APPENDIX. 53 

Table 33. — Rate of seasoning of western red cedar poles at Los Angeles, Cal.a 



Duration 
of season- 
ing. 


Summer cut. 


Fall cut. 


Winter cut. 


Spring cut. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. . 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Months. 

1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 


Pounds. 
6 42.4 


Per cent 
of dry 

weight. 
133.0 


Pounds. 
6 42.4 


Per cent 
of dry 

weight. 
133.0 


Pounds. 
6 42.4 


Per cent 

of dry 

weight. 

133.0 


Pounds. 
6 42.4 


Per cent 

of dry 

weight. 

133.0 






























C38.12 
33.0 
31.0 
29.3 
28.0 


109.5 
81.3 
70.3 
61.0 
53.8 










C36.12 

28.25 
26.30 
25.30 


98.5 
55.2 
44.5 
39.0 










c32.5 
31.1 
30.0 
2S.5 
26.5 
25.0 
23.5 
23.46 


78.6 
70.9 
64.8 
56.6 
45.6 
37.4 
29.1 
28.9 






C33.0 
29.0 
26.5 
25.5 


81.3 
59.3 
45.6 
40.1 































































o Based on four hundred 40-foot poles. The average volume of 300 poles was 27.34 cubic feet. Oven dry 
weight determined by sections cut from 12 poles, 18.2 pounds per cubic foot. 
b Green weight based on weights of 25 summer cut poles taken immediately after cutting, 
c Weight on arrival at Los Angeles, Cal., from three to seven months after cutting. 



^■34 

i 



28 















■s 






















N 






%K 


* N S 




N 


<H. 






X 


















N. 






N. 


., 


^ 


?■ 






S 
















N 


N 








\ 


V 

\ 




























b 






s 














* 














^> 


s°<-- 






\ \ 




































Vs. 




































i 










- 









































































































O I Z 3 4- 5 6 7 O 9 /O // A? /3 At /S /S 17 

juir At/6, sept, ocr. Nov. oec. jan. fee. map. app. may junejuly aug. sept. oct. now. 

T/ME SEASONING -MONTHS 



Fig. 10. — Rate of seasoning western red cedar poles, Los Angeles, Cal. 



54 



PRESERVATIVE TREATMENT OF POLES. 



Table 34. — Rate of seasoning of western yellow pine -poles at North Fork, Madera County, 

Cal.a 



Duration 
of season- 
ing. 


Autumn cut. 


Winter cut. 


Spring cut. 


Summer cut. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Weight 

per cubic 

foot. 


Moisture 
content. 


Months. 

1 
2 
3 
4 
5 
6 
7 
8 
9 
10 


Pounds. 
64.1 
54.0 
51.3 
52.6 
54.1 
50.4 
46.0 
41.7 
37.6 
33.7 
30.3 


Per cent 

of dry 

weight. 

144.7 

106.1 

95.8 

100.8 

106.5 

92.4 

75.6 

59.2 

43.5 

28.6 

15.6 


Pounds. 
66.6 
62.6 
56.2 
47.7 
40.4 
36.0 
32.8 


Per cent 
of dry 
weight. 
154.2 
138.9 
114.5 
82.1 
54.2 
37.4 
25.2 


Pounds. 
65.2 
51.5 
44.4 
38.8 
36.2 
32.6 


Per cent 
of dry 
weight. 
148.9 
96.6 
68.5 
51.9 
38.2 
24.4 


Pounds. 
64.8 
40.3 
33.8 
31.8 


Per cent 
of dry 
weight. 
147.3 
53.8 
29.0 
21.4 



































































a Based on four hundred 40-foot poles. Oven dry weight, 26.2 pounds per cubic foot. Average volume 
8.1 cubic feet. 






APPENDIX. 



55 



66 








V 


























\ 


















62 

60 
SB 
56 
E4 

rise 
I so 

*< 48 
tj 

§3 

5) 46 
<J 

n' 44 


V* 






\ 


k 


























\ 


























1 


























' 1 




























\ A 
























































ft 


























\ ^> 




1 0, 


























1 f> 

1 r 


i 


























i 






\ 

40 
38 
36 




































































































































3Z 

30 























































/S/.9 
Z44-.3 
/36.B 

/aao' 

/E/.4- 

//3.y 

/OS./ 
98. S 
9D.8 
83.£ 
75.6 
B7.9 
60.3 

sa.7 

■45.0 
37.4- 

29.8 

a a./ 

/•4.S 



O / B 3 4- 5 6 7 8 9 /O // /2 /3 

OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE JULY AUB. SEPT. OCT. 
T/ME SEASON/NS-MONTHS 

Fig. 11.— Rate of seasoning of western yellow pine poles, Madera County, Cal. 



o 



